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WORKS    OF  C.    G.   ELLIOTT,  C.E., 

PUBLISHED  BY 

JOHN  WILEY  &  SONS. 

Engineering  for  Land  Drainage. 

A  manual  for  laying  out  and  constructing  drains  for 
the  improvement  of  agricultural  lands.  i2mo,  viii-|- 
232  pages,  41  figures,  6  full-page  half-tones.  Cloth, 
$1.50. 

Practical  Farm  Drainage. 

A  manual  for  farmer  and  Student.  Second  Edi- 
tion, Rewritten.  lamo,  ix+  188  pages,  46  figures. 
Cloth.  $1.50. 


ENGINEERING 
FOR    LAND    DRAINAGE, 


4  MANUAL  FOR  LAYING  OUT  AND  CONSTRUCT 

JNG  DRAINS  FOR  THE  IMPROVEMENT 

OF  AGRICULTURAL  LANDS. 


BY 

CHARLES  G.   ELLIOTT,  C.E., 

Mem.  Am.  Soc.  C.  E., 
Author  of '^  Practical  Farm  Drainage.^* 


FIRST  EDITION', 
FOURTH   THOUSAl^^D. 


NEW  YORK: 

JOHN  WILEY  &  SONS. 

London:  CHAPMAN  &  HALL,  Limited. 

1909. 


Umv.  'Faum 


Un] 


Copyright,  1903, 

BY 

CHARLES  G.  ELLIOTT. 


iUibrrt  fintmmanlt  mtii  CUotnttang 
^m  fork 


PREFACE. 


This  brief  treatise  on  drainage  engineering  is  in- 
tended for  the  use  of  those  who  are  charged  with  the 
responsibility  of  making  plans  for  and  executing  drain- 
age improvements.  It  puts  the  experience  and  practice 
of  years  into  a  form  which  will  be  available  to  others 
who  wish  to  quickly  acquire  the  principles  and  practice 
of  land  drainage. 

Much  more  might  be  said  on  some  of  the  subjects, 
but  the  busy  man  of  to-day  prefers  to  have  the  informa- 
tion he  seeks  in  concise  form  rather  than  to  select  what 
he  desires  from  a  more  voluminous  work. 

The  hydraulics  of  drainage  cannot  be  computed  with 
as  much  accuracy  as  may  be  done  in  some  other 
branches  of  engineering,  owing  to  the  uncertain  data 
available  and  the  variable  conditions  which  must  be 
met.  For  this  reason  formulas  of  less  refinement  than 
are  thought  essential  to  some  other  hydraulic  work  may 
be  used  in  making  drainage  computations.  Good  judg- 
ment should  always  be  exercised  in  applying  data  to 
formulas  in  the  class  of  work  treated  of  in  this  book. 
The  practical  adaptation  of  accurate  and  systematic 
methods  in  dealing  with  land  drainage  questions  is  re- 
garded by  the  author  as  highly  essential  to  the  successful 
prosecution  of  such  work. 

Complicated  and  merely  theoretical  engineering  is  to 
be  avoided.     Simple  and  practical  methods  which  are 

iii 

185859 


iv  PREFACE. 

of  general  application  should  be  especially  sought  for 
and  learned.  It  has  been  the  purpose  of  the  author  to 
emphasize  and  make  clear  those  points  which  the  stu- 
dent, the  busy  agriculturist,  and  the  practical  engineer 
should  know. 

Charles  G.  Elliott. 

Washington,  D.  C, 
November,  1902. 


CONTENTS. 


CHAPTER  L 

INTRODUCTION. 

rA6B 

The  Drainage  Engineer — The  Agriculturist  and  Soil  Drainage. ...       i 
CHAPTER  n. 

SOILS. 

Origin  of  Soils — Transported  Soils — Alluvial  Soils — Sedentary  Soils 
— Organic  Matter  of  the  Soil — Kinds  of  Soils — Each  Soil  an 
Individual — Drainage  Properties  of  Soils  and  Sub-soils — Water 
of  the  Soil— Water  of  the  Soil  that  is  Used  by  Plants— Experi- 
mental Investigations— Soil  Structiire — Capillary  Movement  of 
Water — Effect  of  Fertilizers  upon  Soil  Moisture — Percolation 
through  Frozen  Ground — Heaving  of  Soils — Conservation  of 
Soil  Moisture I2 

CHAPTER  in. 

LAND  DRAINAGE   PRACTICE. 

Drainage  Practice— Underdrainage — Plane  of  Saturation — Sources 
of  Water  Affecting  the  Soil — Systems  of  Tile  Drains — Principles 
to  be  Used  in  Locating  Drains — Data  Required  for  Locating 
Drains 35 

CHAPTER  IV. 

LEVELLING   AND  TOPOGRAPHY. 

Levelling — Levelling  Instruments — Taking  Levels — Drainage  Topo- 
graphy— The  Preliminary  Survey — With  Boundary  Line   as 

V 


VI  CONTENTS. 

PACK 

Base — ^Watercourse  as  Base — Method  by  Central  Base  Line — 
Record  of  the  Work — Topography  by  Contour  Lines — Practical 
Hints 52 

CHAPTER  V. 

LAYING  OUT   DRAINS    IN   THE   FIELD. 

Staking  Out  Drains — Designating  Drains — Levelling  Drains  and 
Keeping  the  Notes — Notes  for  Platting — A  Common  Datum — 
The  Profile — Compass  Surveying  for  Drainage  Work — Keeping 
Compass  Notes 71 

CHAPTER  VL 

FIXING  THE  GRADE   OF  DRAINS. 

Grade  of  Drains — Depth  of  Drains — Frequency  of  Drains — Prelimi- 
nary Estimate  of  Length  of  Drains 85 

CHAPTER  Vn. 

MAPS   AND   RECORDS. 

Drafting    Instruments — Platting    Compass    Notes    and  Angles — 

Making  the  Map — Copying  Maps 95 

CHAPTER  VIII. 

GRADING   THE   DITCHES   FOR  TILE. 

Digging  Ditches  and  Laying  the  Tile — Difficulties  in  Constructing 
Tile  Drains — Inspecting  Tile  Drains— Filling  the  Ditches — 
Marking  Out  Tile-ditches  with  the  Tlow — Outlet  Protection — 
The  Silt-basin — Digging  Tile- ditches  with  Machines— Contracts 
for  Construction  of  Tile  Drains 103 

CHAPTER  IX. 

FLOW  OF   WATER   THROUGH   PIPES. 

Formulas  for  Flow — Flow  of  Water  through  Tile  Drains — Applica- 
tion of  the  Formula — Examples  of  the  Use  of  the  Formula — 
Limitations  of  Size,  Grade,  and  Length  of  Drain 126 


CONTENTS.  Vii 

CHAPTER  X. 

SIZE   OF   LATERAL  DRAINS. 

PAGB 

Provisions  for  Unusual  Rainfall — Selection  of  Tile — Tabulating  Tile 

for  Drains 144 

CHAPTER  XL 

OPEN   DRAINS. 

Grade  for  Open  Ditches — Mean  Velocity  of  Flow — Relation  of 
Breadth  and  Depth  of  Channel  to  Surface  and  Mean  Velocity 
— Curvature  of  Ditches — Form  and  Depth  of  Ditches — Capacity 
Required  for  Open  Ditches — Quantity  of  Water  per  Acre  to  be 
Removed — Formula  for  Flow  in  Open  Ditches — Waste  Banks 
and  Berm — Surveys  for  Open  Ditches— Computing  Excavation 
— Ditching  with  Steam-dredges — Ditching  with  Teams — Dis- 
charge of  Side  Ditches  into  Main — Special  Form  for  Ditches. . .   150 

CHAPTER  Xn. 

DRAINAGE   OF   BARNYARDS,  CATTLE-LANES,    ETC. 

Drainage  of  Barnyards — Taking  Surface-water  into  Underdrains — 
Drainage  of  Cellars  and  Residence  Grounds — Drainage  of 
Fruit  Orchards 179 

CHAPTER  XIII. 

ROAD     DRAINAGE. 

Earth  Roads — Gravel  and  Earth  Roads — Seepage-water  on  Roads 
— Surface  Drainage  of  Hill  Roads — Culverts  and  Cross-drains 
— Drainage  of  Paved  Roads — Combined  Brick  and  Clay  Road.   187 

CHAPTER  XIV. 

DRAINAGE   DISTRICTS. 

Working  Plans — Theory  of  the  Classification  of  Lands— Classifi- 
cation for  Assessment  Purposes — Classification  Map — Com- 
puting Assessment  Roll — Mutual  Cooperative  Drainage 199 


Vlll  CONTENTS. 

CHAPTER  XV. 

ESTIMATES   OF  COST. 

VAOB 

Schedule  for  Making  Estimates — Total  Estimate, — Estimated  Profit 
on  the  Investment — Cost  of  Work  under  Drainage  District 
Organization 209 

CHAPTER  XVI. 
Benefits  and  Profits  of  Land  Drainage 216 


ENGINEERING  FOR  LAND   DRAINAGE. 


CHAPTER   I. 
INTRODUCTION. 


THE      DRAINAGE     ENGINEER — THE      AGRICULTURIST 
AND   SOIL   DRAINAGE. 

The  Drainage  Engineer, 

The  importance  of  the  work  of  the  drainage  engineer 
may  in  a  measure  be  appreciated  when  we  consider  the 
magnitude  of  land  drainage  projects  which  have  been 
executed  during  the  century  which  has  just  closed. 
The  immense  tracts  of  land  in  the  Old  World  which  have 
been  reclaimed  from  the  inroad  of  river  and  sea  and  are 
now  the  greatest  food-producing  lands  in  the  world  are 
monuments  to  the  skill  of  engineers  who  planned  and 
executed  these  works.  None  of  these  drainage  projects 
has  been  carried  out  without  the  aid  of  engineers  of 
high  ability,  as  well  as  of  great  energy  and  originality. 
He  who  has  in  this  way  contributed  to  the  world's 
wealth  and  the  happiness  of  man  is  as  worthy  of  high 
esteem  as  he  who  discovers  some  rich  island,  or  by  his 


2  ENGINEERING   FOR    LAND    DRAINAGE. 

researches  ascertains  the  means  by  which  a  dread  dis- 
ease may  be  averted. 

The  civilizing  effects  of  the  drainage  of  these  great 
tracts  upon  the  people  immediately  concerned  are  diffi- 
cult to  measure.  It  is  sufficient  to  say,  however,  that 
it  has  had  no  small  part  in  leading  men  away  from 
primitive  superstitions  and  rude  practices  to  higher  am- 
bitions, nobler  impulses,  and  purer  morals.  It  is  said 
that  when  the  drainage  of  the  North  Level,  a  part  of 
the  celebrated  Fens  of  England,  seemed  assured  one  of 
the  Fen  poets  made  the  following  versified  predictions : 

"  With  a  change  of  elements  suddenly 
There  shall  a  change  of  men  and  manners  be : 
Hearts  thick  and  tough  as  hides  shall  feel  remorse 
And  souls  of  sedge  shall  understand  discourse: 
New  hands  shall  learn  to  work,  forget  to  steal ; 
New  legs  shall  go  to  church,  new  knees  shall  kneel." 

Not  only  this,  but  in  the  development  of  the  fertility 
of  a  large  area  of  all  grain-producing  agricultural  lands 
drainage  has  been  extensively  practised,  and  is  justly 
regarded  as  one  of  the  most  necessary  adjuncts  of  suc- 
cessful soil  culture. 

Land  drainage  in  this  country  has  had  its  principal 
growth  during  the  last  twenty  years.  Its  practice 
reaches  from  the  simple  drainage  of  a  garden  costing 
only  a  few  dollars  to  that  of  tracts  containing  thousands 
of  acres,  involving  elaborate  plans  and  the  expenditure 
of  large  sums  of  money.  It  includes  the  drainage  of 
all  kinds  of  lands  which  require  it,  either  for  profit  or 
for  health,  and  hence  embraces  a  wider  range  of  topics 
than,  upon  first  thought,  seems  to  be  involved. 

The   drainage   engineer  should   be   qualified  for  his 


INTRODUCTION.  3 

chosen  field  of  work,  understanding  that  this  is  an  age 
of  specialties,  and  that  without  devoting  thought  and 
investigation  to  his  particular  pursuit  he  cannot  expect 
to  be  proficient  in  it.  He  should  understand  the  drain- 
age characteristics  and  capabilities  of  different  soils, 
and  treat  them  according  .to  their  needs,  keeping  in 
mind  the  ultimate  use  which  is  to  be  made  of  them. 
The  various  means  of  accomplishing  this  work  in  the 
most  thorough  and  economical  manner  belong  to  his 
special  field  of  investigation  and  practice.  There  are 
sound  principles  upon  which  drainage  is  founded,  but 
there  are  no  **  standard  plans"  for  accomplishing  it, 
as  there  are  for  the  construction  of  many  other  kinds  of 
engineering  work.  Writers  upon  the  subject  of  drain- 
age frequently  make  a  mistake  along  this  line  by  recom- 
mending certain  plans  and  methods  of  work  for  all 
localities  without  regard  to  differences  of  soil,  climate, 
physical  conditions,  or  the  use  to  which  the  land  will 
be  put  after  it  is  drained.  He  who  measures  his  skill 
in  drainage  by  his  success  with  one  piece  of  work  in 
one  locality  may  easily  flatter  himself  unduly,  for  the 
reason  that  scarcely  any  two  projects  can  be  planned 
and  worked  alike  with  equal  success. 
>  There  is  a  difference  between  the  work  of  the  sur- 
veyor and  that  of  the  engineer,  though  both  may  be 
done  by  the  same  person.  The  work  of  gathering  defi- 
nite data  and  facts  and  putting  them  in  orderly  form  for 
future  use  is  strictly  the  work  of  the  surveyor.  He 
may  do  all  this  and  not  have  the  requisite  skill  to  use 
the  data  thus  obtained  in  designing  and  laying  out  an 
effective  and  economical  drainage  system.  The  sur- 
veyor secures  data;  the  engineer  plans  and  executes 


4  ENGINEERING   FOR    LAND    DRAINAGE. 

from  data.  One  collects  material;  the  other  builds 
from  the  material  collected.  In  making  his  surveys 
the  engineer  should  aim  to  secure  sufficient  information 
to  properly  design  the  work,  yet  not  so  much  that  the 
labor  and  expense  involved  in  securing  it  would  not  be 
justifiable  from  a  strictly  business  point  of  view. 

The  drainage  engineer  deals  with  corporations,  com- 
missioners, and  private  individuals  as  their  professional 
expert  and  counsellor.  He  should  make  his  employ- 
er's case  his  own,  and  use  his  best  energies  to  solve 
the  difficulties  which  arise,  having  due  regard  to  sound 
practice  and  enduring  results.  He  should  put  himself 
in  harmony  with  the  work  and  constantly  keep  in  mind 
the  specific  object  which  he  is  expected  finally  to  reach. 

He  should  be  proficient  in  the  art  of  clearly  repre- 
senting his  data  and  plans  by  creditable  drawings  and 
concise  language.  His  statements  should  be  divested 
of  all  unnecessary  technicalities  in  order  that  they  may 
be  plain  to  the  common  reader.  This  does  not,  of 
course,  imply  that  his  knowledge  or  experience  should 
be  meager,  but  that,  out  of  the  abundance  of  his  in- 
formation, he  should  select  that  part  which  will  bear 
upon  the  case  in  hand,  and  so  express  it  that  it  will  be 
available  to  others. 

With  truth  it  may  be  said  that  greater  proficiency  is 
needed  in  the  practice  of  drainage  engineering  than  at 
present  exists.  The  work  has  not  been  systematized 
as  has  other  professional  work,  nor  investigated  with 
that  thoroughness  which  its  importance  demands. 
Much  trouble  arises  both  from  incompetence  of  en- 
gineers and  over-competence — if  the  expression  may 
be  allowed — of  their  employers.     As  before  intimated, 


INTRODUCTION.  5 

the  engineer  must,  if  possible,  look  through  the  eyes 
of  his  employer  in  order  to  get  his  view  of  the  matter 
and  appreciate  the  difficulties  as  they  appear  to  him. 
If  after  investigation  the  two  differ  in  opinion  and  the 
employer  is  unwilling  to  accept  the  plans  and  methods 
of  the  engineer  without  modifications  which  seem  to 
him  unwise,  he  should,  at  least,  put  himself  on  record 
as  not  endorsing  the  objectionable  features. 

Above  all,  the  drainage  engineer  should  exercise  a 
high  order  of  common  sense,  good  judgment,  and  hon- 
esty in  the  management  of  the  work  intrusted  to  him. 
He  should  not  let  his  ideas  of  engineering  nicety  carry 
him  to  a  point  where  much  of  the  work  he  does  will 
have  no  particular  value,  and  yet  he  should  seek  to  do 
his  work  in  a  professional  way  and  with  accuracy.  A 
well-balanced  enthusiasm  should  characterize  him  in  all 
of  his  work,  and  by  fairness  in  dealing  he  should  secure 
the  confidence  of  all  with  whom  he  has  professional  or 
business  relations. 


The  Agriculturist  and  Soil  Drainage. 

The  soil  is  the  farmer's  business  capital.  He  has 
exchanged  a  certain  sum  of  money  for  it,  or  come  into 
possession  of  it  by  inheritance,  and  must  now  look  to 
its  products  for  returns.  He  has  before  him  for  solu- 
tion the  various  problems  connected  with  soil  culture 
and  its  relation  to  profit  and  loss.  The  soil  becomes  a 
receptacle  for  his  money  and  a  field  for  intelligent 
labor.  Good  husbandry  strenuously  insists  on  a  thor- 
ough preparation  of  the  seed  bed  and  an  intelligent 
after-cultivation  of  the  plant.     It  also  demands  a  wise 


6  ENGINEERING   FOR    LAND   DRAINAGE. 

and  economic  use  of  the  products  of  the  soil,  be  they 
grain,  forage,  or  fruits.  The  end  to  be  sought  in  all 
of  this  is  that  the  farmer  may  receive  a  profit  over  all 
and  still  have  his  capital,  the  soil,  intact  and  unim- 
paired. 

One  of  the  well-recognized  means  of  bringing  about 
this  gratifying  result — making  the  farm  pay — is  to  re- 
move the  surplus  moisture  from  the  soil.  By  surplus  is 
meant  more  than  is  needed.  The  surplus  moisture 
should  be  removed  through  the  soil,  if  possible,  rather 
than  over  it.  The  drainage  of  the  soil  is  by  no  means 
an  innovation,  nor  is  it  a  work  remaining  yet  in  an  ex- 
perimental stage,  except  as  regards  a  better  under- 
standing of  its  application  to  various  soils,  and  for  the 
purpose  of  demonstrating  the  scientific  changes  which 
result  from  practical  work  along  this  line. 

The  growth  of  the  drainage  improvement  for  agri- 
cultural purposes  has  always  been  governed  by  the  en- 
vironment of  the  farmer.  While  he  had  sufficient  land 
which,  in  its  natural  condition,  Avas  drained  and  re- 
quired only  the  ordinary  and  primitive  methods  of  cul- 
tivation, there  was  no  occasion  for  adding  to  his  arable 
estate  those  lands  which  would  require  more  than  the 
ordinary  expenditure  of  money  and  labor.  That  time 
is  past.  Now  every  progressive  farmer  looks  upon 
each  unimproved  acre  of  land  as  an  item  on  his  farm 
expense  account.  For  does  he  not  pay  taxes  upon 
it  in  common  with  his  most  productive  land?  Does 
it  not  cost  him  as  much  to  cultivate  as  does  the  adjoin- 
ing field  of  rich  and  friable  loam?  Is  it  not  a  blot 
upon  an  otherwise  fair  rural  picture,  to  say  nothing  of 
the  financial  features  which  with  the  farmer  and  business 


INTRODUCTION.  7 

man  are  more  weighty?  While  this  is  true  of  the  small 
farmer  who  delights  in  high-grade  and,  sometimes, 
artistic  agriculture,  there  are  large  tracts  of  fertile  land 
lacking  only  suitable  drainage  to  fit  them  for  the  most 
profitable  cultivation.  The  enterprising  agriculturist, 
be  his  interests  large  or  small,  will  find  an  ample  field 
for  the  exercise  of  such  knowledge  as  he  may  choose 
to  acquire  in  the  theory  and  practice  of  land  drainage. 
Nor  should  he  fail  to  avail  himself  of  all  opportunities 
presented  for  mastering  this  useful  subject.  The  fact 
that  our  national  government  and  our  State  experiment 
stations  are  devoting  marked  attention  to  such  subjects 
as  "The  Movement  of  Ground-water,"  **  Moisture 
and  Crop  Distribution, "  *  *  Mechanics  of  Soil  Moisture, ' ' 
*' Moisture  Determination  in  Soils,"  indicates  that 
these  subjects  and  their  bearing  upon  soil  drainage  are 
worthy  of  the  most  careful  study  by  practical  men. 

In  the  discussion  of  topics  pertaining  to  general  farm- 
ing, fruit-growing  or  stock-raising  as  given  in  the  agri- 
cultural papers  or  at  the  sessions  of  Farmers'  Institutes, 
the  subject  of  soil  drainage  takes  a  prominent  place, 
and  the  value  of  such  an  improvement  of  the  soil  is  em- 
phasized and  its  advantages  enlarged  upon  by  all  pro- 
gressive farmers.  Like  every  other  operation  in  which 
the  management  of  the  soil  is  concerned  there  is  a 
right  way  and  a  wrong  way  of  performing  it:  there 
may  be  a  good  way  and  a  better  way;  there  is  only 
one  best  way.  Some  soils  require  no  artificial  drain- 
age, some  a  little,  and  some  a  great  deal,  in  order  to 
yield  the  best  results.  Good  judgment  and  some 
knowledge  are  required  to  adapt  the  method  of  im- 
provement to  the  land  to  be  treated.     The  landowner 


S  ENGINEERING   FOR   LAND   DRAINAGE. 

should  perform  the  work  well  without  unnecessary  cost. 
He  should  know  how  the  work  should  be  done,  or  be 
able  to  employ  some  one  with  sufficient  skill  and  pro- 
fessional honesty  to  do  the  work  for  him.  There  is  no 
mystery  connected  with  the  theory  and  practice  of  land 
drainage,  as  some  would  have  us  believe,  neither  is  an 
instinct  born  in  men  which  will  relieve  them  from  the 
necessity  of  acquiring  knowledge  of  this  work  in  the 
old-time  way. 

Drainage  practice  must  be  adapted  to  the  needs  of 
each  tract  of  land  to  be  improved.  In  other  words, 
each  farm,  and  in  many  cases  each  field,  presents  a 
special  problem  in  drainage.  How  much  more  diverse, 
then,  must  be  the  practice  in  different  States  and  lati- 
tudes.^ The  land-drainer  should  not  think  that  a  method 
which  has  proved  efficient  in  one  locality  will  necessa- 
rily be  the  best  in  another,  or  that  when  he  has  suc- 
cessfully drained  one  tract  or  farm  he  can  drain  any 
other  by  the  same  plan.  Yet  the  principles  are  the 
same  for  all;  it  is  only  the  application  of  them  that 
varies. 

Some  ultra-practical  men  discourage  the  farmer  from 
attempting  to  learn  the  history  and  progress  of  land 
drainage,  urging  that  the  present  state  of  the  practice 
is  sufficient.  Life  is  not  too  short  for  a  man  to  avail 
himself  of  the  experience  of  others  along  any  line  of 
work  in  which  he  is  interested,  and  he  acts  wisely  when 
he  seeks  to  acquire  all  information  pertaining  to  his 
business.  It  is  not  proposed,  however,  in  these  pages 
to  give  such  a  history  but  to  outline  in  plain  language 
the  best  practice  at  the  present  time. 

The    subject   will    be  treated  from  an    engineering 


INTRODUCTION.  9 

standpoint,  but  that  need  not  deter  the  farmer  from 
becoming  conversant  with  the  entire  subject,  nor  from 
studying  it  in  a  scientific  way.  It  is  a  subject  which 
has  merited  the  careful  attention  of  intelHgent  land- 
owners and  of  eminent  hydraulic  engineers. 

The  profits  accruing  from  the  drainage  of  fertile  land 
are  of  two  kinds:  first,  the  increased  yield  of  grasses, 
cereals,  and  fruits  which  has  a  direct  money  value  to 
the  producer;  second,  the  increased  healthfulness  of  the 
community  where  drainage  has  reclaimed  all  of  the 
waste  land.  This  latter  has  a  money  value  which  is 
difficult  to  measure.  The  following  example  clearly 
illustrates  both  of  the  above  statements: 

The  Indiana  Bureau  of  Statistics  made  an  investiga- 
tion of  the  influence  of  tile-drainage  on  health  and 
crops,  selecting  a  single  township  in  the  State  where 
drainage  was  one  of  the  marked  improvements,  and 
taking  a  period  of  five  years  before  drainage  began, 
and  five  years  after  most  of  the  township  had  been  tile- 
drained.  By  consulting  farmers  who  lived  in  the  town- 
ship during  both  periods,  they  found  that  the  average 
crop  of  wheat  in  the  five  years  before  drainage  was  9J 
bushels  per  acre.  The  same  land  after  drainage  for 
five  consecutive  years  produced  an  average  of  19J 
bushels  per  acre.  The  average  yield  of  corn  in  the 
first  five  years  was  31^  bushels  per  acre.  In  the  five 
years  after  drainage  the  average  yield  was  74J  bushels 
per  acre.  The  physicians  who  answered  calls  in  the 
township  were  requested  to  report  from  their  books, 
and  it  was  found  that  in  the  first  five  years  there  had 
been  1480  cases  of  malarial  disease.  In  the  second 
period  there  had  been  only  490  cases  of  malarial  dis- 


to      ENGINEERING  FOR  LAND  DRAINAGE. 

ease.  With  such  facts  before  us  it  will  require  no  argu- 
ment to  convince  the  average  citizen  that  drainage  has 
largely  increased  the  health  and  wealth  of  that  com- 
munity, and  thereby  added  materially  to  the  prosperity 
of  the  State. 

This  subject  involves  the  conservation  of  soil  moisture 
as  well  as  the  removal  of  surplus  water,  the  care  of 
private  and  public  roads,  the  sanitary  drainage  of  the 
home  and  grounds,  subjects  which  receive  too  little 
thought  from  the  average  landowner.  One  who 
chooses  to  devote  a  small  fraction  of  his  time  to  ac- 
quiring a  knowledge  of  the  principles  and  best  practice 
along  these  lines,  and  to  apply  the  same  in  the  light  of 
his  own  observation  and  common  sense,  may  become 
sufficiently  proficient  to  direct  the  operations  on  his  own 
estate,  in  fact  become  his  own  engineer  if  he  cares  to 
engage  in  that  business. 

The  writer  appreciates  the  many  practical  difficulties 
which  present  themselves  to  the  landowner  who  per- 
sonally attends  to  all  of  the  detail  work  connected  with 
the  improvement  of  his  farm  and  home,  as  well  as  those 
that  must  be  met  by  the  investor  who  improves  his 
holdings  for  the  purpose  of  deriving  a  larger  annual 
revenue  from  the  capital  invested.  Many  drainage 
projects  necessitate  cooperation  on  the  part  of  interested 
landowners,  without  which  private  interests  suffer, 
and  will  continue  to  suffer,  until  certain  men  who  op- 
pose the  combined  effort  become  persuaded  that  it  will 
be  to  their  profit  to  join  the  movement  under  equitable 
provisions  of  the  law,  bear  their  proportion  of  the  ex- 
pense, and  receive  the  benefit  accruing  from  the  work. 
For  this  reason  as  well  as  others  heretofore  mentioned, 


INTRODUCTION.  1 1 

landowners  should  be  conversant  with  the  principles, 
benefits,  and  best  practice  of  land  drainage,  not  neglect- 
ing to  acquire  information  regarding  the  legal  drainage 
rights  of  adjoining  landowners  and  the  general  prin- 
ciples of  cooperative  work. 


CHAPTER  II. 
SOILS. 

The  soil,  one  of  the  essentials  to  the  existence  and 
well-being  of  the  human  race,  is  one  of  the  most  com- 
plex products  of  nature.  With  all  the  acquirements  of 
which  man  can'boast  he  cannot  create  a  pound  of  soil, 
understand  the  intricacies  of  its  composition,  nor  yet 
avail  himself  fully  of  the  wealth  locked  up  within  this 
most  familiar  of  all  natural  objects.  Nature  has  ap- 
parently brought  out  the  choicest  selections  from  her 
storehouse  and  placed  them  at  the  service  of  man  in 
the  form  commonly  known  as  soil.  Its  varieties  are 
unnumbered,  its  capabilities  unmeasured,  and  its  adapt- 
ability to  supply  the  needs  of  man  only  partially  under- 
stood. 

Origin  of  Soils. — Soils  are  broken  and  decomposed 
rocks.  Before  the  external  forces  of  nature  acted  upon 
them  they  were  as  barren  and  useless  as  the  clean 
peaks  of  the  mountains  or  the  washed  rock  in  the  bed 
of  the  stream.  Many  of  the  changes  to  which  the 
original  rocks  were  subjected  in  bringing  them  into  the 
new  and  useful  combination  are  unknown,  but  the  gen- 
eral process  can  be  quite  accurately  understood  from 
examples  which  may  be  witnessed  in  nature  by  any 
interested  observer. 

The  mosses  which  are  found  on  the  rocks  are  a  low 

12 


SOILS.  13 

order  of  vegetation  subsisting  upon  elements  contained 
in  the  air  and  in  the  crude  rock.  Not  many  years 
elapse  until  the  moss  thickens  to  such  an  extent  that  it 
appears  to  be  growing  in  a  thin  bed  of  soil,  while  di- 
rectly beneath  it  the  rock  is  decomposed  and  portions 
of  it  drop  away  in  scales  as  soon  as  the  covering  is 
removed.  This  is  accomplished  by  the  combined  ac- 
tion of  heat  moisture  and  the  changes  incident  to  cli- 
matic influences.  The  mosses  continue  to  grow,  bits  of 
decomposed  rock  drop  and  lodge  at  the  base,  forming 
a  shelving  bed  of  soil  which  readily  supports  vegetable 
growth.  Rains  possibly  wash  it  away  to  some  low  val- 
ley, there  to  be  mingled  with  decomposed  rocks  from 
other  localities,  all  of  which  in  time  build  the  fertile  soil. 
In  it  may  be  found  numberless  kinds  of  rocks,  and  as 
vegetation  increases  portions  of  organic  matter  mingle 
with  the  material  and  contribute  the  humus  so  valuable 
for  the  production  of  certain  crops.  It  seems  incredible 
that  the  hardest  of  rocks  known  should  succumb  to  the 
action  of  climate  and  be  reduced  to  a  condition  of  impal- 
pable fineness,  yet  a  little  observation  on  the  part  of  the 
investigator  will  confirm  the  statement.  The  reader 
has  doubtless  observed  a  tree  growing  upon  an  appar- 
ently dry  rock.  A  nearer  view  discloses  crevices  which 
the  roots  of  the  tree  have  penetrated.  The  crevices 
are  lined  with  rock  in  all  stages  of  disintegration  which 
increase  year  by  year  with  the  growth  of  the  tree. 
Further  than  this,  the  force  of  the  wedge  which  the 
root  forms  splits  off  a  ledge  of  rock  which  in  turn 
disintegrates  and  adds  to  the  volume  of  forming 
soil. 

A  ledge  of  red    shale   disintegrates   rapidly  under 


14  ENGINEERING   FOR    LAND   DRAINAGE. 

climatic  changes,  and  the  result  is  a  belt  of  red  clay  soil 
on  a  bench  of  the  hillside  below.  In  such  cases  all 
stages  of  soil  formation  may  be  seen  from  the  rock-like 
shale  to  the  plastic  clay.  The  lava-covered  slopes  of 
volcanic  mountains  become  covered  with  soil  in  the 
same  manner.  Time  and  the  changes  incident  to  a 
humid  climate  will  convert  lava,  at  one  time  a  seethmg 
mass,  into  a  fruitful  soil. 

One  peculiarity  of  these  natural  changes  is  that  the 
rocks  by  being  brought  to  such  a  state  of  comminution 
lose  their  identity.  The  minute  particles  of  different 
rocks  become  so  thoroughly  blended  that  their  original 
condition  can  only  be  inferred  by  fragments  of  un- 
changed rock  which  may  chance  to  be  found  in  the 
mixture.  The  hundreds  of  forms  known  to  the  geol- 
ogist and  mineralogist  under  distinctive  names,  each 
one  of  which  when  chemically  analyzed  is  found  to 
contain  from  six  to  twelve  elements,  will  never  be 
known  after  being  changed  to  soil.  Hence  it  is  only 
the  general  processes  which  relate  to  the  origin  of  soils 
that  are  of  particular  interest  in  the  discussion  of  this 
subject.  The  composition  of  soils  can  be  known  only 
through  chemical  analyses,  and,  since  the  same  element 
is  found  in  a  variety  of  rocks,  it  is  impossible  to  deter- 
mine from  such  analyses  what  the  original  rocks  were. 
A  physical  analysis  will  determine  the  comparative 
fineness  of  the  particles  constituting  the  soil,  a  matter 
of  much  importance  in  its  treatment. 

Sedentary  Soils  are  those  which  remain  where  they 
are  formed  and  constitute  a  covering  for  the  rock  from 
which  they  originated.  They  have  usually  little  depth 
and  comprise  but  a  small  part  of  useful  soils. 


SOILS.  1 5 

Transported  Soils  are  those  which  have  been  re- 
moved from  their  original  rock  beds  by  the  action  of 
glaciers,  floods  of  water,  or  by  streams  which  have  car- 
ried soil  particles  in  suspension  and  deposited  them  as 
sediment.  In  this  way  decomposed  rocks  from  widely 
distant  localities  have  become  mixed  together  in  an 
inseparable  mass.  One  form  of  transported  soils  is 
known  as  the  drift  which  originated  during  the  Glacial 
Epoch,  a  period  when  the  present  surface  of  the  coun- 
try was  covered  to  a  great  depth  with  fields  of  ice. 
This  kind  of  soil  is  usually  distinguished  by  rounded 
rocks  of  various  sizes  called  boulders,  and  by  fragments 
of  rocks  whose  edges  have  been  rounded  by  friction, 
all  of  which  are  incorporated  with  the  soil  proper.  As 
might  be  correctly  inferred,  the  varieties  of  soil  found 
in  the  area  affected  by  glacial  action  include  every  pos- 
sible shade  of  difference.  The  moving  glacier  from 
whose  melting  mass  rocks  and  clumps  of  soil  were  con- 
stantly being  deposited,  and  subsequently  ground  by 
the  passing  mountain  of  ice,  formed  one  of  the  later 
geological  epochs  and  one  which  is  of  great  interest 
and  importance  to  the  northern  part  of  the  United 
States  and  Canada  and  as  far  west  as  western  Iowa. 

Alluvial  Soils  consist  of  worn  and  rounded  mate- 
rials which  have  been  transported  by  the  agency  of 
moving  water  and  deposited  as  sediment.  .  The  pos- 
sible conditions  under  which  soils  can  be  formed  in  this 
way  are  without  number.  Alluvial  deposits  have  been 
formed  in  all  periods  of  the  world's  history.  Water 
trickling  down  a  granite  slope  carries  forward  the  kao- 
linite  arising  from  decomposition  of  feldspar,  and  the 
first  hollow  gradually  fills  up  with  a  bed  of  clay.      In 


«F    THE 


UNIVERSITY 


1 6  ENGINEERING   FOR   LAND   DRAINAGE. 

valleys  are  thus  deposited  the  gravel,  sand,  and  rock 
dust  detached  from  the  slopes  of  the  neighboring 
mountains.  Lakes  and  gulfs  become  filled  with  silt 
brought  into  them  by  streams.  Alluvium  is  found  be- 
low as  well  as  above  the  drift,  and  recent  alluvium  in 
the  drift  region  is  very  often  composed  of  drift  material 
rearranged  by  water  currents. 

Organic  Matter  of  the  Soil. — As  before  noted,  vege- 
tation plays  an  important  part  in  the  conversion  of 
rocks  into  soil.  The  lower  orders  of  plants,  such  as 
the  lichens  and  mosses,  prepare  the  way  for  grasses  and 
forests.  The  decay  of  vegetation  adds  to  the  soil  a 
brown  or  black  friable  substance  commonly  known  as 
humus  which  gives  off  gases  and  aids  in  the  further 
conversion  of  inert  material  into  productive  soil.  The 
gases  such  as  carbonic  acid  and  ammonia  are  largely 
held  in  the  soil,  their  volume  depending  upon  the  quan- 
tity of  vegetable  matter  which  the  soil  contains,  and 
the  supervention  of  warm  wet  weather. 

The  proportion  of  carbonic  acid  contained  in  the 
pores  of  different  kinds  of  soil  compared  with  that  found 
in  the  ordinary  atmosphere  is  strikingly  shown  in  the 
following  analysis  made  by  Boussingault  and  Lewy. 

CARBONIC    ACID    IN     ID,  GOO    PARTS  OF    AIR  BY  WEIGHT. 

Ordinary  atmosphere 6 

Air  from  sandy  subsoil  of  forest 38 

'    ''      ''      loamy        ''        ''     ''      124 

•  *      '  *       surface  soil        ' '     "      1 30 

Air  from  surface  soil  of  vineyard 146 

*'      **                  *'         '*  old  asparagus  bed. .  .  122 

**      **                  **         '^  newly  manured  land.  233 

**      **                  *'         "  pasture  land 270 

**     **                 **        rich  in  humus 543 


SOILS. 


17 


Kinds  of  Soils. — Soils  are  known  to  the  agriculturist 
by  names  drawn  from  their  external  appearance  or 
from  some  peculiarity  which  they  show  when  worked. 
Many  of  such  names  have  a  local  application  only. 

Clayey  Soils  are  commonly  characterized  by  ex- 
treme fineness  of  texture  and  by  great  retentive  power 
for  water.  When  subjected  to  a  mechanical  analysis 
their  particles  are  found  to  be  the  finest  of  all  soil  par- 
ticles. 

Sandy  Soils  are  those  which  contain  80  per  cent  or 
more  of  sand.  Silica  or  grains  of  quartz  withstand  the 
disintegrating  agencies  beyond  all  others,  and  hence 
when  once  in  the  soil  never  change  their  form.  How- 
ever, there  are  all  kinds  of  sandy  soils,  from  the  one 
which  contains  but  little  to  the  soil  carrying  90  per 
cent  of  sand. 

Gravelly  Soils  contain  an  abundance  of  small  stones 
or  pebbles  which  in  themselves  are  worthless,  but  aid 
in  a  mechanical  way  to  keep  the  soil  open,  assist  in 
drainage,  and  store  solar  heat.  Many  gravelly  soils  are 
exceedingly  fertile. 

Loamy  Soils  are  those  intermediate  in  character  be- 
tween sandy  and  clayey.  They  can  be  worked  freely, 
not  having  sufficient  clay  to  be  heavy,  nor  sand  and 
gravel  in  such  large  quantities  as  to  make  them  too 
open . 

To  express  suggested  differences  we  have  the  terms 
Sandy  Loam^  Sandy  Clay,  Gravelly  Loam,  and  Grav- 
elly Clay. 

Gumbo  Soils  are  loams  with  sufficient  plastic  clay 
mixed  with  them  to  make  them  exceedingly  sticky  or 
adhesive  when  wet.      They  are  fertile  soils  when  prop- 


I 


1 8      ENGINEERING  FOR  LAND  DRAINAGE. 

erly  cultivated.  In  some  instances  a  layer  of  gumbo 
is  found  beneath  a  fine  bed  of  loam,  and  supports  it  as 
a  subsoil. 

Muck  is  a  black  soil  composed  largely  of  vegetable 
matter  and  is  found  in  swamps.  It  frequently  requires 
exposure  to  the  atmosphere  for  a  time  before  it  can  be 
treated  as  a  workable  soil. 

Peat  is  partially  decayed  swamp  turf  which  when 
dry  will  burn  readily.  The  underlying  bed  is  usually 
muck  or  blue-black  clay. 

Hard-pan  is  the  name  applied  to  a  tough,  impene- 
trable layer  underlying  a  fairly  fertile  soil.  A  hard- 
pan  proper  is  made  up  of  soil  particles  which  are  being 
cemented  together  again  by  the  solutions  of  lime,  iron, 
or  silicates  that  descend  through  the  soil.  Commonly 
speaking,  however,  any  hard  clay  subsoil  is  termed 
hard-pan. 

Each  Soil  an  Individual. 

Each  soil  possesses  a  composition  and  character  of 
its  own,  and  it  follows  that  its  capabilities,  require- 
ments, and  treatment  should  be  taken  up  individually. 
Soil  investigations  are  necessarily  experimental,  be 
they  made  with  reference  to  productive  capabilities, 
drainage  properties  or  irrigation  possibilities.  Each 
case  should  be  taken  up  by  itself  and  studied  with 
special  reference  to  its  character  and  condition.  When 
plants  are  chemically  analyzed  they  are  found  to  con- 
tain elements  found  in  the  soil  with  the  exception 
of  aluminum.  However,  the  element  which  appears 
most  abundant  in  the  plant  is  frequently  found  in  the 
most  meager  quantities  in   the  soil  which  produces  it, 


SOILS.  19 

suggesting  the  fact  now  well  understood  that  it  is  not 
so  much  the  quantity  of  a  needed  element  in  the  soil 
which  is  required  as  its  availability  to  plants.  The 
conditions  induced  by  proper  tilth  moisture,  and  the  use 
of  such  fertilizers  as  will  by  chemical  combinations  re- 
lease and  put  in  proper  condition  for  plant  assimilation 
the  otherwise  inert  elements  of  the  soil,  are  matters 
determined  by  experiment. 

Drainage  P  1^0 per  ties  of  Soils  and  Subsoils, 

Soil  is  the  surface  land  that  is  cultivated  and  which 
produces  vegetable  growth.  In  general  terms,  it  is  the 
surface  stratum  of  earth. 

Subsoil  is  the  stratum  of  earth  upon  which  the  soil 
rests. 

The  dividing  line  between  the  two  is  not  clearly 
marked  as  a  rule,  so  that  the  terms  are  usually  under- 
stood to  apply  respectively  to  that  depth  of  surface  land 
which  may  be  cultivated,  and  the  layer  immediately  be- 
neath. Soils  and  subsoils  are  of  almost  every  con- 
ceivable color,  composition,  and  physical  structure. 
Their  treatment  for  the  growth  of  plants  and  for  the 
support  of  important  engineering  and  architectural 
structures,  and  their  investigation  respecting  their  re- 
lation to  human  diseases,  engaged  the  attention  of  men 
of  thought  for  ages.  Men  and  animals  move  upon 
them,  plants  derive  their  nutriment  from  them,  and 
water  is  stored  among  their  particles.  The  soil  is  a 
great  laboratory  wherein  is  developed  and  from  which 
is  dispensed  the  Creator's  supplies  for  man's  temporal 
wants. 


20  ENGINEERING   FOR    LAND   DRAINAGE. 

With  respect  to  their  drainage  we  speak  of  them  as 
open  and  retentive,  the  terms  expressing,  not  their 
power  of  retaining  certain  quantities  of  water,  but  the 
readiness  or  rapidity  with  which  water  moves  among 
the  particles  when  a  means  of  drainage  is  offered.  Be- 
tween the  very  open  soils  and  the  very  retentive  ones 
there  are  numberless  degrees  of  difference  which  must 
be  expressed  by  qualifying  terms  if  they  are  properly 
described. 

This  may  be  illustrated  by  a  few  examples  which 
will  serve  to  show  the  bearing  of  these  terms.  A  soil 
or  subsoil  composed  largely  of  sand  or  gravel  offers  but 
slight  resistance  to  the  movement  of  water  among  the 
particles,  so  that  a  single  drain  as  an  outlet  relieves  the 
soil  of  drainage-water  for  a  very  considerable  distance 
from  it.  There  are  instances  of  drainage  districts  in 
which  the  opening  of  a  single  deep  channel  has  drained 
to  a  considerable  degree  of  thoroughness  certain  lands 
lying  a  mile  each  side  of  it.  There  are  other  localities 
where  the  effect  of  such  drain  does  not  extend  one  hun- 
dred feet,  and  still  others  where  forty  feet  is  the  limit. 
Upon  these  natural  conditions  of  the  soil  largely  de- 
pend the  means  that  should  be  employed  to  properly 
drain  it. 

The  relation  of  the  soil  to  the  subsoil  should  also  be 
carefully  observed.  The  subsoil  may  be  compact  and 
retentive,  while  the  soil  directly  above  it  may  be  open, 
or  the  opposite  conditions  may  exist.  The  subsoil 
may  not  be  parallel  to  the  surface  in  its  general  con- 
formation, but  a  retentive  clay  may  crop  out  near  the 
surface  at  some  points,  and  recede  in  others,  thus  form- 
ing  pockets   or  basins  underneath   the  surface  where 


SOILS.  21 

water  is  retained,  much  to  the  injury  of  the  surface  soil. 
These  frequently  occur  upon  the  tops  of  hills,  or  upon 
hillside  slopes  where  the  surface  indications  do  not  lead 
one  to  suspect  such  conditions.  Fig.  i  represents  a 
section  of  soil  of  this  character. 


Fig.  I. — Section  showing  Effect  of  Clay  Subsoil  upon  Natural  Drainage. 

The  characteristics  of  soils  as  indicated  above  are 
general,  but  are  sufficient  to  point  out  what  should  be 
looked  for  when  their  drainage  is  undertaken.  These 
general  qualities  are,  however,  dependent  upon  many 
minute  differences,  such  as  mechanical  fineness  and 
physical  structure  of  the  particles,  the  attraction  which 
their  surface  has  for  water  films,  the  chemical  compo- 
sition of  the  component  parts,  and  many  other  essential 
particulars  which  have  been  observed  and  are  still  being 
investigated  by  the  soil  physicist. 

Water  of  the  Soil, 

Water  which  affects  the  soil  exists  in  two  conditions. 

Hydrostatic  Water  is  visible  to  the  eye  and  free  to 
obey  the  laws  of  gravity.  It  is  water  which  is  found 
between  the  particles  of  the  soil  and  passes  off  through 
drains  either  natural  or  artificial.  It  is  frequently 
spoken  of  as  drainage-water. 

Capillary  Water  is  that  which  is  held  within  the  fine 
pores  of  the  soil  by  the  surface  attraction  of  its  par- 


22  ENGINEERING   FOR    LAND   DRAINAGE. 

tides.       It   is  commonly  called   moisture  and  is  the 
water  which  is  left  in  the  soil  after  it  is  drained. 

Speaking  in  general  terms,  about  50  per  cent  of  the 
volume  of  a  soil  is  empty  space,  that  is,  it  contains  only 
air  and  water.  The  results  of  experiments  hereafter 
given  show  that  the  volume  of  empty  space  ranges 
from  37  per  cent  as  found  in  sandy  soils  to  65  per  cent 
in  soils  composed  largely  of  clay.  This  space  is  so 
divided  up  by  the  very  large  number  of  grains  of  soil 
that  the  spaces  between  the  grains  are  extremely 
small.  When  a  soil  is  only  slightly  moist  the  water 
clings  to  the  soil  grains  in  a  thin  film.  The  force 
which  holds  water  to  the  grain  of  soil  is  called  surface 
tension.  The  water  is  called  capillary  water.  It  is 
like  a  soap-bubble  with  a  grain  of  sand  or  clay  inside 
instead  of  air.  Where  the  grains  come  together  the 
films  are  united  into  a  continuous  film  of  water  through- 
out the  soil.  If  more  water  enters  the  soil,  the  film 
thickens  and  there  is  less  exposed  water  surface.  If 
the  empty  space  is  completely  filled  with  water,  gravity 
alone  will  act  with  its  greatest  force.  If  the  soil  is 
nearly  dry,  there  will  be  a  great  deal  of  this  exposed 
water  surface,  a  great  amount  of  surface  tension,  and 
hence  gravity  will  have  no  effect.  In  other  words, 
there  will  be  no  hydrostatic  water,  since  the  force  of 
surface  tension  is  able  to  retain  the  entire  supply  of 
water  about  the  particles  of  which  the  soil  is  composed. 

Hydrostatic  water  moves  through  the  soil  with 
greater  or  less  rapidity  and  freedom,  according  to  the 
resistance  which  the  soil  particles  offer  to  its  passage. 
It  moves  upward  only  when  forced  to  do  so.  It  moves 
downward   and   laterally  in   obedience   to  the  laws  of 


SOILS.  23 

gravity.  Capillary  water  moves  in  any  direction  in 
accordance  with  the  laws  of  capillary  attraction  which 
exists  between  a  liquid  and  a  solid  when  brought  into 
contact. 

The  movement  of  hydrostatic  and  capillary  water 
through  the  soil  is  necessary  to  its  healthy  condition  as 
far  as  the  growth  of  plants  is  concerned.  Capillary 
water  moves  to  supply  the  demand  of  evaporation, 
plant-roots,  and  other  portions  of  the  soil  which  are 
deficient  in  moisture.  Water  moves  downward  from 
the  surface  by  gravity  and  supplies  needed  capillary 
water  which  is  held  by  the  surface  tension  of  the  soil 
particles.  The  remainder  passes  off  as  hydrostatic 
water  through  drains  either  natural  or  artificial,  or,  suit- 
able drainage  not  being  provided,  it  remains  to  retard 
the  growth  of  plants  and  in  other  ways  injure  the  soil. 

Water  of  the  Soil  that  is  Used  by  Plants, 

Plants  take  their  nutriment  from  the  soil  by  means  of 
rootlets  which  grow  in  close  contact  with  soil  particles. 
All  plant-food  taken  through  these  rootlets  must  be  in 
solution  and  in  the  condition  of  capillary  water  or,  as  it 
is  commonly  called,  moisture.  In  nature's  preparation 
of  plant-food  mineral  matter  must  be  dissolved,  organic 
matter  be  decomposed,  gases  absorbed  by  water,  and 
the  whole  stored  away  in  liquid  form  within  the  minute 
pores  of  the  soil,  there  to  be  seized  upon  by  the  root-- 
lets  of  plants  and  thence  appropriated  to  their  growth. 

It  matters  not  how  much  fertility  there  may  be  pres-- 
ent  in  the  soil,  if  it  is  not  put  in  this  form  it  is  not  avail-' 
able  to  plants.     Hydrostatic  water  is  useful  only  in 


24  ENGINEERING   FOR   LAND    DRAINAGE. 

replenishing  the  supply  of  capillary  water.  When  this 
is  accomplished,  the  surplus  should  be  drawn  off  by 
the  process  of  drainage  in  order  that  air  and  gases  may 
take  its  place.  These  in  connection  with  heat  and 
moisture  aid  in  the  decomposition  of  organic  and  min- 
eral components  of  the  soil  which  constitute  its  fertility. 
Excess  of  water  retards,  and  in  many  cases  altogether 
prevents  this  process. 

It  is  the  province  of  drainage  to  remove  the  surplus 
water  and  retain  the  capillary  water,  since  it  is  in  the 
latter  form  only  that  water  is  appropriated  by  useful 
plants.  By  the  removal  of  hydrostatic  water  the 
chemical  forces  of  the  soil  are  permitted  to  work  freely 
in  their  laboratory,  and  thus  prepare  the  elements  of 
the  soil  for  plant  use. 

Experimental  Investigations, 

Many  of  the  changes  which  take  place  in  soils  by 
reason  of  the  presence  of  water  in  varying  quantities 
are  now  being  made  the  subject  of  careful  examination 
at  some  of  our  experiment  stations.  This  is  particu- 
larly true  of  mechanical  analyses  of  soils,  and  observa- 
tions upon  the  movement  of  water  in  soils  possessing 
different  physical  characteristics.  It  is  interesting  to 
note  that  the  operations  and  effects  of  drains  upon  the 
soil  as  heretofore  recorded  by  close  observers,  agree 
very  closely  with  the  results  of  experiments  made  in 
recent  years  for  the  purpose  of  ascertaining  the  facts  with 
scientific  precision.  To  the  soil  physicist,  the  engineer, 
and  the  observing  agriculturist  these  investigations 
are  in  every  way  interesting  and  useful.      While  experi- 


SOILS.  25 

ments  along  this  line  are  by  no  means  complete,  yet 
much  work  has  been  done  which  bears  directly  upon 
the  theory  and  practice  of  land  drainage,  some  of  the 
results  of  which  will  be  briefly  outlined  in  this  chapter. 


Soil  Structure, 

Soils  and  subsoils  are  composed  of  solid  grains  of 
variable  sizes  which  touch  each  other  at  certain  points 
on  their  surfaces.  The  comparative  size  of  soil  grains 
varies  greatly,  and  is  an  important  and  interesting  sub- 
ject for  investigation. 

According  to  a  mechanical  analysis  made  in  1891  at 
the  Maryland  Experiment  Station,  the  diameter  of  soil 
grains  for  the  several  materials  named  is  as  follows: 

Coarse  sand i  to  .5   millimeters 

Medium  sand 5      to  .25  '' 

Fine  sand 25    to  .1  •* 

Very  fine  sand I      to  .05  ** 

Silt 05    to  .01  ** 

Fine  silt 01    to  .005  ** 

Clay 005  to  .0001 

Note, — MilHmeter  =  .03937  in. 


«( 


This  is  only  comparative,  as  by  the  method  used  for 
analysis  the  absolute  size  could  not  be  obtained,  but  a 
reliable  method  for  classifying  soils  with  reference  to 
the  size  of  soil  grains  was  hit  upon  and  used. 

The  empty  space  between  these  grains  has  also  been 
determined  for  a  variety  of  soils,  the  following  being 
the  result  of  some  of  the  experiments : 


26  ENGINEERING   FOR  LAND   DRAINAGE. 

Sandy  truck  soil 37-29  per  cent 

Wheatland 42.72     *'      " 

Barren  clay 47. 19     **     .** 

Gummy  land 61.54 

Pipe-clay 65.12 


By  comparing"  the  fineness  of  the  grains  with  the 
volume  of  empty  space,  it  is  seen  that  the  finer  the 
grains  the  greater  the  volume  of  empty  space  a  soil  con- 
tains. That  is,  a  clay  holds  or  is  capable  of  holding 
27.8  per  cent  of  volume  of  water  more  than  the  sandy 
soil  noted,  while  the  grains  of  the  clay  are  about  five 
hundred  times  smaller  than  those  of  the  sandy  soil.  By 
comparing  the  results  of  several  analyses  of  soils  and 
subsoils,  it  is  found  that  the  results  which  appear  in  the 
tables  referred  to,  characterize  all  soils. 

These  investigations  show  that  clays  are  made  up  of 
the  smallest  grains,  and  contain  the  greatest  volume  of 
empty  space,  and  from  the  results  of  other  experiments 
it  appears  that  the  volume  of  empty  space  of  soils  in 
general  is  in  direct  proportion  to  the  per  cent  of  clay 
which  they  contain.  When  this  space  becomes  charged 
with  water,  the  rate  of  movement  under  a  given  head, 
as  would  be  readily  and  correctly  inferred,  is  more 
rapid  through  a  sandy  soil  than  through  one  composed 
of  a  considerable  per  cent  of  clay.  While  the  sandy 
soil  contains  less  total  volume  of  space  and  hence  will 
hold  a  smaller  volume  of  water  than  the  clay  soil,  the 
spaces  are  larger  individually  than  those  in  the  clay 
and  hence  less  resistance  is  offered  to  the  flow  of  water 
through  them. 

Experiments  were  made  at  the  Station  with  a  num- 


SOILS.  27 

ber  of  different  soils  with  reference  to  this  point.  Tubes 
were  filled  with  the  varieties  of  earth  to  be  investigated, 
and  water  passed  through  the  soil  under  a  constant  free 
head  of  two  inches  above  the  soil.  The  time  which, 
under  these  conditions,  one  inch  of  water  passed  through 
three  inches  of  soil  was  noted.  The  following  are  a 
few  of  the  results  obtained:  A  sandy  soil  containing 
3.9  per  cent  of  clay,  time  5  J  minutes.  A  heavy  red 
clay  with  28.8  per  cent  of  pure  clay,  time  133  minutes. 
A  black  gummy  land  with  large  grains  of  sand  and  26 
per  cent  of  clay,  16  minutes. 

These  experiments  bring  out  the  facts  regarding  the 
mechanical  structure  of  soils  from  which  may  be  drawn 
some  very  helpful  conclusions.  It  must  be  kept  in 
mind,  however,  that  natural  soil  conditions  are  often 
different  from  those  existing  in  the  portion  of  soil  which 
has  been  experimented  with.  The  ground  beneath  its 
surface  contains  seams  and  channels  made  by  the  en- 
trance and  decay  of  plant-roots,  or  is  changed  by  the 
separation  of  joint  clays  into  little  cubes,  or  possibly 
the  surface  has  been  puddled  by  some  means,  thereby 
essentially  changing  the  structure  in  such  a  way  as  to 
give  us  quite  different  results.  The  outlet  for  water  is 
not  always  at  hand  as  provided  for  in  experiments. 
The  percolation  of  water  through  the  surface  soil  is 
affected  by  cultivation  and  by  the  application  of  fer- 
tilizers, the  latter  having  the  effect  of  changing  the 
arrangement  of  the  soil  grains  and  making  the  soil 
more  retentive  of  moisture. 


28      ENGINEERING  FOR  LAND  DRAINAGE. 


Capillary  Movement  of  Water, 

During  the  year  1 897  very  satisfactory  experiments 
were  conducted  by  the  Division  of  Soils  of  the  U.  S. 
Department  of  Agriculture  for  the  purpose  of  determin- 
ing the  quantity  of  moisture  present  in  soils  at  differ- 
ent depths  by  means  of  the  electrical  method.  This 
method  is  based  upon  the  changing  electrical  resistance 
between  two  plates  which  are  buried  in  the  soil,  and 
consists  in  measuring  the  resistance  by  means  of  a 
mechanism  devised  for  the  purpose.  The  study  of  the 
results  obtained  by  these  experiments  in  connection 
with  the  rainfall  record  and  the  drainage  of  the  soil, 
will  well  repay  the  agriculturist  or  engineer  who  is  in- 
terested in  soil  study. 

The  table  on  p.  29,  taken  from  Bulletin  No.  12, 
U.  S.  Department  of  Agriculture,  Division  of  Soils, 
is  interesting  and  useful  in  showing  the  per  cent  of 
water  carried  by  a  soil  at  Washington,  D.  C,  under 
three  different  conditions:  the  first,  growing  wheat; 
the  second,  cultivated  bare,  and  the  third,  well 
mulched. 

From  other  experiments  noted  in  the  same  Bulletin 
the  following  are  selected  for  the  purpose  of  showing 
the  per  cent  of  clay  and  corresponding  per  cent  of  water 
carried  by  the  several  soils  noted,  during  the  growing 
season : 

At  Newbern,  N.  C,  on  the  best  type  of  early  truck 
land  the  soil  to  a  depth  of  three  or  four  feet  has  about 
2.8  per  cent  of  clay,  and  averages  about  8.5  per  cent 
of  water  for  the  crop  season. 


J 


SOILS. 


29 


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30  ENGINEERING   FOR    LAND   DRAINAGE. 

At  Windsor,  Conn.,  light  sandy  tobacco  soil  contain- 
ing 1 .3  per  cent  of  clay  averages  10  per  cent  of  water 
for  the  growing  season. 

Heavy  limestone,  tobacco,  corn,  wheat,  and  grass 
land  at  Litiz,  Pa. ,  containing  36  per  cent  of  clay,  carries 
23  per  cent  of  moisture. 

At  Lexington,  Ky. ,  blue  grass  and  tobacco  soils 
which  maintain  about  35  per  cent  of  clay,  carry  22  per 
cent  of  moisture. 

Results  of  experiments  at  Germantown,  Ohio,  on 
cigar  tobacco  soil  which  is  also  good  for  corn,  wheat 
and  grass,  show  27^  per  cent  of  clay  in  the  subsoil  and 
22  per  cent  of  moisture. 

Further  experiments  only  confirm  the  above  and 
indicate  that  our  heavy  soils  suitable  for  grass  and 
grain  contain  from  20  to  36  per  cent  of  clay  and  carry 
from  20  to  23  per  cent  of  moisture,  while  the  light, 
sandy  truck  soils  have  as  low  as  3  per  cent  of  clay  and 
carry  8  per  cent  of  moisture. 

Compare  these  results  with  the  volume  of  empty 
space  in  the  several  examples  of  soils,  and  we  can  de- 
termine with  approximate  correctness  the  volume  of 
water  that  must  be  removed  from  a  saturated  soil  be- 
fore it  becomes  fitted  for  the  several  crops  which  it  is 
desired  to  grow. 

Effect  of  Fertilizers  upon  Soil  Moisture, 

From  some  experiments  made  by  the  Department  it 
is  shown  that  the  addition  of  certain  fertilizers  placed  in 
the  soil  causes  it  to  retain  moisture  with  greater  tenac- 
ity.     This  is  accounted  for  by  supposing  that  the  ac- 


SOILS. 


31 


tion  of  the  fertilizer  upon  the  particles  of  soil  reduces 
their  size,  thereby  making  them  more  retentive  of 
moisture.  This,  however,  has  not  been  demonstrated. 
It  is  a  fact  well  known  to  every  observing  cultivator 
of  the  soil  that  good  barnyard  manure  spread  upon  a 
portion  of  the  field  conspicuous  for  its  dryness  will  re- 
sult in  a  good  showing  of  moisture  during  the  dry  sea- 
son. If  a  soil  is  too  wet,  it  is  frequently  made  more  so 
by  the  addition  of  well  rotted  manure ;  but  if  it  be  un- 
derdrained,  the  results  will  be  most  pleasing  and  profit- 
able. 

Percolation  through  Frozen  Ground. 

The  impression  is  quite  general  that  while  the  ground 
is  frozen  there  can  be  little  or  no  percolation  through 
it.  This  is  far  from  being  true.  As  soon  as  the  sur- 
face of  the  ground  becomes  slightly  softened  by  the 
action  of  snow  or  rain,  the  shrinkage-cracks,  worm- 
perforations,  and  root-courses  always  present  in  the  soil, 
at  once  become  available  for  the  passage  of  drainage- 
water,  and  as  a  result  underdrains  may  be  operative  in 
midwinter.  Water  is  filtered  through  the  soil  and  its 
fertilizing  ingredients  deposited  in  the  soil  below  the 
frost  line. 

The  freezing  of  the  soil,  however,  is  of  great  assist- 
ance in  ''fining  "  the  surface,  disintegrating  the  grains 
composing  the  subsoil,  and,  as  above  noted,  adding 
fertility  by  the  process  of  filtering  surface  water.  It  is 
readily  understood  that  frost  penetrates  a  drained  soil 
deeper  than  a  saturated  one  because  the  atmosphere 
takes  the  place  of  removed  water.     For  this  reason  the 


32  ENGINEERING    FOR    LAND    DRAINAGE. 

drained  soil  thaws  earlier  in  the  spring.  The  warm 
surface  air  enters,  and  the  soil  becomes  fitted  for  culti- 
vation several  days  earlier  than  one  which  contains  too 
much  water. 


Heaving  of  Soils, 

One  great  benefit  derived  from  proper  drainage  is 
that  soils  do  not  heave  to  such  an  extent  as  to  injure 
plants.  When  soils  which  are  saturated  with  water 
freeze,  the  water  expands  about  one  eighth  in  volume, 
and  as  a  result  the  surface  of  the  soil  is  raised,  carrying 
with  it  plant-roots  which  are  not  anchored  below  the 
frost  line.  A  thaw  melts  the  ice,  and  the  soil  under 
ordinary  conditions  settles  back  to  its  original  position, 
but  plants  with  shallow  rooting  remain  in  their  raised 
position.  Alternate  freezing  and  thawing,  which  take 
place  in  some  localities  several  times  during  the  winter, 
not  infrequently  leave  the  roots  of  clover,  wheat,  and 
rye  partially  or  wholly  out  of  the  ground.  Fields  of 
clover  and  wheat  have  been  ruined  in  this  way,  and 
meadows  of  timothy  and  orchard-grass  have  been 
greatly  injured  during  one  winter.  If  the  soil  is  not  sat- 
urated, that  is,  if  there  is  air  space  in  it  and  the  moist- 
ure has  sufficient  space  for  expansion  when  it  freezes 
without  materially  disarranging  the  soil  grains,  no  such 
injurious  effects  as  have  been  named  will  follow.  The 
heaving  effect  of  frost  upon  soils  may  be  demonstrated 
in  an  interesting  way  by  the  following  experiment. 
Before  the  ground  freezes  in  the  fall  drive  pegs  of  about 
one  inch  section  and  six  inches  long  flush  with  the  sur- 
face  of  the   ground,   some  in  soils  well  drained,  and 


SOILS. 


33 


others  in  wet  soils.  At  the  opening  of  the  spring  many 
of  the  pegs  which  were  driven  in  the  wet  soil  will 
be  found  partly  raised  out  of  the  ground,  and  some 
of  them    will    be    found    lying  upon   the  surface,    as 


Fig.  2. — Heaving  of  Wet  Soils. 

shown  in  Fig.  2.  Those  driven  into  well-drained  soil 
will  be  found  to  have  been  but  slightly  moved  by  the 
frost. 

The  heaving  of  the  soil  has  much  to  do  with  the  un- 
settled condition  of  undrained  dirt  roads,  for  the  reason 
that  the  soil  grains  become  completely  disarranged  and 
thrown  out  of  their  natural  position  so  that  the  com- 
pactness of  the  load-bearing  surface  of  the  road  is  de- 
stroyed. 

Conservation  of  Soil  Moisture, 

While  the  removal  of  surplus  moisture  from  the  soil 
is  of  first  importance,  the  retention  of  a  proper  quantity 
is  equally  necessary.  The  object  of  underdrainage  is 
to  secure  and  maintain  a  golden  mean  between  a  dry 
and  a  wet  soil.  All  observing  and  thorough  cultivators 
are  particular  during  the  growing  season  to  give  the 
soil  a  thorough  surface  cultivation  as  soon  after  every 
rain  as  practicable.  This  pulverization  of  the  surface 
— the  finer  the  better — has  been  found  to  serve  the  pur- 
pose of  a  mulch  in  dry  weather,  and  to  be  conducive 
to  plant  growth  especially  in  underdrained  soils. 


34  ENGINEERING   FOR   LAND   DRAINAGE. 

The  benefit  as  explained  by  some  is  due  to  the  dry- 
ness of  the  covering,  which  is  secured  by  frequent  cul- 
tivation, and  which  induces  the  formation  of  a  new 
moisture  line  just  beneath  the  surface.  Another  ex- 
planation, and  the  more  tenable  one,  is  this:  The  rain- 
fall saturates  the  surface  and  to  some  extent  causes  the 
soil  particles  to  assume  a  new  and  closer  relation  to 
each  other.  These  when  dried  by  the  sun  and  wind 
form  a  thin  surface  crust,  which  increases  the  tension 
and  capillarity  of  the  soil  particles  so  that  moisture 
from  below  is  carried  rapidly  to  the  surface  and  evapo- 
rated. Cultivation  breaks  up  this  compact  condition 
of  the  soil  and  retards  the  capillary  action  of  its  surface 
layer.  Frequent  surface  culture,  which  is  now  recog- 
nized as  a  most  important  adjunct  to  successful  soil  cul- 
tivation, is  made  possible  by  underdrainage,  since  the 
soil  can  be  cultivated  soon  after  any  rain  without  risk 
of  injury. 


CHAPTER   III. 
LAND   DRAINAGE   PRACTICE. 

Land  Drainage  is  the  removal  of  surplus  water  from 
the  soil. 

Various  descriptive  terms  are  used  in  connection  with 
the  word  drainage  according  to  the  purpose  for  which 
this  removal  is  effected.  When  done  for  the  better 
growth  and  protection  of  useful  plants  it  is  called 
Agricultural  Drainage.  When  done  for  the  better 
construction  and  maintenance  of  public  highways  it  is 
called  Road  Drainage.  When  done  for  the  benefit  of 
health,  either  in  city  or  country,  it  is  called  Sanitary 
Drainage. 

It  will  be  the  object  of  these  pages  to  discuss  these 
questions  and  describe  the  methods  which  engineers, 
or  those  expecting  to  act  as  such,  are  called  upon 
to  deal  with  in  the  planning  and  execution  of  work 
pertaining  to  land  drainage. 

The  definition  of  drainage  indicates  that  it  is  a  very 
simple  operation,  yet  its  practical  attainment  is  accom- 
panied with  no  little  uncertainty  unless  correct  prin- 
ciples and  methods  are  followed  out.  Investigations 
along  this  line  are  somewhat  difficult,  for  the  reason 
that  the  action  of  drains  is  hidden  from  the  eye,  and  is 
known  only  by  the  effect  which  is  produced.  Nature 
has  in  many  localities   provided  thorough  drainage  of 

35 


36  ENGINEERING   FOR   LAND   DRAINAGE. 

the  soil.  In  others  it  is  only  partly  accomplished,  the 
remainder  of  the  work  to  be  done  by  the  enterprise  of 
man. 

He  who  drains  land  for  any  purpose  whatever  should 
put  it  down  as  a  first  principle  that  he  is  only  aiding 
Nature,  and  hence  he  must  work  in  accordance  with 
her  laws.  We  frequently  take  too  much  credit  to 
ourselves  in  thinking  that  we  have  invented  some 
new  method,  when  we  have  only  developed  the  plans 
as  they  have  been  pointed  out  to  us  by  Nature.  A 
very  little  artificial  work  in  addition  to  natural  ad- 
vantage will  sometimes  bring  about  complete  drainage, 
while  in  other  cases  great  labor  and  expense  will  be 
necessary  to  accomplish  results  no  more  complete. 

The  first  question  to  be  asked  where  agricultural 
drainage  is  contemplated  is,  will  the  land  be  productive 
after  drainage.?  If  this  question,  after  proper  investi- 
gation, must  be  answered  negatively,  the  matter  should 
be  dropped,. if  the  agricultural  value  of  the  land  is  the 
only  one  to  be  considered.  Some  wet  lands  have  no 
productive  value  before  drainage,  nor  will  they  after- 
wards, though  it  may  be  said  for  our  encouragement 
that  such  cases  are  exceptional. 

The  second  question  is,  can  the  land  be  drained,  and 
if  so,  how,  and  at  what  cost.-*  It  will  be  the  writer's 
object  to  deal  with  this  question  in  its  practical  details, 
under  appropriate  divisions  of  the  subject. 

Under  drainage. 

No  soil  is  completely  drained  of  its  surplus  water, 
unless  it  is  done  by  the  process  known  as  underdrain- 


LAND   DRAINAGE   PRACTICE.  37 

age.  It  may  be  done  by  the  means  which  Nature  has 
provided,  as  is  the  case  where  the  subsoil  contains  a 
stratum  of  sand,  gravel,  or  other  permeable  material, 
into  which  water  from  above  finds  its  way  by  gravity, 
and  thence  passes  to  some  water-course  with  which  the 
drainage  stratum  has  free  communication.  This  gives 
the  most  complete  drainage  possible.  When  natural 
underdrainage  is  wanting,  or  is  defective,  then  artificial 
drainage  should  be  resorted  to.  Round  drain-tiles  are 
the  most  suitable  for  this  purpose,  and  are  universally 
acknowledged  to  furnish  the  most  serviceable  and  com- 
plete artificial  means  of  draining  the  soil  now  known. 

Water  enters  the  tile  drain  through  the  joints  or  be- 
tween the  ends  of  the  tiles.  Ordinarily  it  enters  from 
the  bottom,  being  brought  there  by  gravity  and  held  to 
the  depth  at  which  it  may  be  in  the  tile  by  the  lateral 
pressure  of  soil  water.  Water  from  the  surface  presses 
directly  downward  until  it  reaches  a  line  where  the  soil 
is  saturated.  It  then  moves  only  as  the  water  below 
the  line  of  saturation  is  drawn  off  by  the  drain,  when 
it  in  turn  passes  downward  and  laterally  until  it  reaches 
the  drain.  The  rapidity  of  this  movement  is  measured 
by  the  hindrance  offered  to  the  water,  by  the  nature  of 
the  soil  particles,  and  by  the  ability  of  the  drain  to  re- 
move water  as  fast  as  it  is  brought  to  it.  The  line  of 
saturation  rises  and  falls  as  the  supply  of  water  in- 
creases or  diminishes,  receding  during  the  time  of  least 
supply  into  the  lowest  plane  it  can  occupy.  At  the 
time  when  the  soil  has  just  ceased  to  supply  drainage 
water  to  the  tile,  a  very  slight  rainfall,  or  even  the 
change  ot  temperature  incident  to  night-time,  will 
cause  the  drain  to  discharge.     No  water  enters  the  tik 


38  ENGINEERING  FOR   LAND   DRAINAGE. 

drain   until   capillary  water   has   been  supplied  to  the 
soil. 

The  material  out  of  which  the  tiles  are  made  does  not 
affect  their  efficiency  as  drains,  nor  the  facility  with 
which  soil  water  enters  the  drain. 


Plane  of  Saturation, 

It  will  be  readily  understood,  from  the  explanation 
just  given  regarding  the  action  of  a  single  drain  upon 
the  soil,  that  as  the  lateral  distance  from  the  drain  is 
increased  the  plane  of  saturation  rises,  for  the  reason 
that  the  water  in  passing  toward  the  drain  encounters 
the  resistance  of  the  particles  of  the  soil,  which  resist- 
ance requires  a  certain  head  to  overcome,  or  there  can 
be  no  movement  of  water.  The  angle  which  a  Hne  in 
this  plane  makes  with  a  horizontal  passing  through  the 
floor  of  the  drain  must  vary  with  the  degree  of  soil  re- 
sistance. Upon  this  depends  the  lateral  distance  to 
which  a  single  line  of  tile  will  drain  the  soil,  and  the 
depth  at  which  drains  should  be  placed.  This  line  of 
saturation  has  been  assumed  from  observations  upon 
the  action  of  drains  to  be  a  curve  of  some  kind,  but 
no  definite  investigations  have  been  made  upon  the 
subject  until  recently. 

In  1 89 1  observations  were  made  at  the  Wisconsin 
Agricultural  Experiment  Station  in  a  tile-drained  field 
bordering  upon  a  lake,  a  part  of  which  was  provided 
with  natural  underdrainage  alone,  for  the  purpose  of 
determining  the  actual  contour  of  the  plane  of  satura- 
tion. The  following  is  a  brief  account  of  the  method 
used  and  the  results  obtained: 


LAND   DRAINAGE   PRACTICE. 


39 


<'  The  lines  of  tile  in  the  field  were  laid  33  feet  apart 
and  about  four  feet  below  the  surface.  Small  wells 
were  sunk  midway  between  the  lines  of  tile  and  were 
therefore  16J  feet  distant  from,  drains  on  either  side. 
The  soil  of  the  field  consists  of  6  or  8  inches  of  medium 
clay  loam,  followed  by  2 J  to  3  feet  of  clay,  below  which 
is  a  stratum  of  rather  coarse  sand,  in  the  upper  surface 
of  which  the  tiles  are  usually  laid.  The  tiles  are  three 
inches  inside  diameter,  and  are  laid  on  a  grade  of  about 
two  inches  in  100  feet.  At  the  time  the  levels  were 
taken  the  tiles  were  discharging  only  one  twentieth  of 
their  capacity. 

**  The  observed  contour  of  ground-water  in  this  field 
at  8  A.  M.,  May  13,  forty-eight  hours  after  a  rainfall  of 
.87  inch,  is  represented  in  Fig.  3.  The  highest  water 
level  in  any  well  between  these  lines  of  tile  on  this  date 
was  one  foot,  in  the  case  of  well  A  measured  above  the 


33  ft. 


E  F 


Fig.  3. — Line  of  Saturation  between  Tile  Drains  48  hours  after  a  Ram< 
fall  of  Y^^  of  an  inch. 


level  of  drain  No.  14.  The  least  was  about  .3  foot,  in 
the  case  of  well  E  above  tile  No.  18.  Both  wells  C 
and  E  were  sunk  into  a  sand  containing  a  considerable 
amount  of  gravel,  and  to  this  fact  is  probably  due  the 
less  steep  gradient  at  these  places.  Between  well  B 
and  tile  16  two  other  wells  were  sunk,  one  two  feet 
from  the   drain,  and  the  other  midway  between   the 


40  ENGINEERING   FOR    LAND    DRAINAGE. 

drain  and  well  B,  In  the  well  two  feet  from  the  drain  the 
water  stood  .3  foot  above  the  top  of  the  tile  and  in  the 
other  .45  foot  above.  The  profile  would  present,  there- 
fore, a  more  or  less  curved  contour,  convex  upward. ' ' 

Prof.  King,  under  whose  direction  the  observations 
were  made,  draws  the  following  conclusions : 
,  **  Assuming  the  water  level  at  the  several  lines  of 
tile  to  be  flush  with  the  tops  of  the  tile,  and  regarding 
the  water  surface  as  presenting  a  right  line  of  section, 
the  mean  gradient  for  the  ground-water  surface  plane 
of  saturation  would  be  i  foot  in  25.3  feet.  There  were 
other  wells  sunk  outside  the  range  of  tile  drains  for  the 
purpose  of  ascertaining  the  height  of  the  ground-water 
above  the  water  surface  of  the  lake.  Of  these  he  says : 
**In  well  29,  150  feet  from  the  lake  shore,  the  water 
stood  7.2  feet  above  the  level  of  the  lake  on  June  27, 
1892,  and  this  would  give  a  gradient  of  i  ft.  in  20.8. 
In  the  case  of  the  well  at  the  Hall  to  which  I  have  re- 
ferred as  having  a  water  level  52  feet  above  the  lake, 
and  situated  about  1250  feet  from  the  shore,  the  mean 
gradient  would  be  i  in  24.04.  In  the  fall  of  1888, 
Sept.  10,  when  the  water  level  in  the  wells  could  not 
have  been  affected  by  lateral  percolation,  the  gradient 
between  well  29  and  the  lake  was  i  in  35.8." 

He  observes  further  that  the  water  line  of  the  tile- 
drained  field  under  consideration  did  not  remain  as  de- 
scribed, but  as  water  was  carried  away  by  the  drains, 
the  line  was  drawn  down  at  a  uniform  rate,  falling  fast- 
est on  the  highest  ground  where  the  level  was  highest. 

These  researches  serve  to  indicate  in  a  tangible  way 
the  relation  of  the  line  of  saturation  to  underdrainage. 
The  method  of  averages  used  by  Prof.  King  in  drawing 


LAND    DRAINAGE    PRACTICE.  4I 

his  conclusions  leads  to  an  error  as  far  as  drainage  is 
concerned.  The  greatest  rise  is  found  to  be  i  foot  in 
16^  feet,  and  the  least  i  foot  in  55  feet. 

Since  soils  in  which  drains  are  placed  may  be  like 
any  one  of  those  upon  which  observations  were  made, 
no  soil  would  be  foU'nd  to  which  an  average  of  widely 
different  results  could  apply  except  by  accident  or  co- 
incidence. It  follows  that 'the  plane  of  saturation  with 
respect  to  the  position  of  tile  drains  must  be  determined 
for  each  kind  of  soil  which  is  to  be  drained.  Sugges- 
tions upon  this  point  will  be  made  when  we  come  to 
consider  the  application  of  these  physical  soil  charac- 
teristics to  the  location  of  drains. 

Sources  of  Water  Affecting  the  Soil. 

In  locating  drains  it  is  necessary  to  consider  the 
source  of  the  water  to  be  removed.  Primarily  the  rain- 
fall is  the  source  of  all  water-supply,  but  in  land  drain- 
age work  it  is  known  by  various  terms  describing  its 
local  source. 

It  is  known  as  surface  water  when  the  direct  rainfall 
rests  upon  or  flows  over  the  surface  of  the  land;  local 
soil  water  when  a  part  of  the  surface  water  sinks  di- 
rectly into  and  saturates  the  soil  and  the  subsoil ;  flood 
water,  when  water  from  some  adjoining  source  flows 
upon  land,  thereby  throwing  a  greater  quantity  of  water 
upon  it  than  the  natural  rainfall  supply;  ooze  or  seep- 
age water  when  it  finds  its  way  through  the  soil  from 
some  higher  elevation,  and  is  arrested  in  its  course  by 
a  less  slope  or  a  change  of  subsoil  structure  (the 
locality  where  the  water  appears  is  called  "  spouty"); 


42  ENGINEERING   FOR   LAND   DRAINAGE. 

spri7ig  water  when  it  proceeds  from  some  distant  and 
constant  source  following  a  channel  of  its  own  until  it 
reaches  a  free  outlet,  where  it  shows  its  presence  in  a 
definite  and  constant  quantity. 

Systems  of  Tile  Drains. 

The  various  arrangements  of  drains  according  to  the 
requirements  of  the  surface  and  soil  to  be  treated  are 
called  systems. 

A  Main  Drain  is  one  which  is  used  to  collect  drain- 
age water  from  smaller  drains  and  conduct  it  to  some 
open  ditch  or  natural  stream. 

A  Sub-Main  is  a  drain  which  discharges  into  a  main, 
and  is  itself  a  receiving-drain  for  lines  of  smaller  tile. 

A  Lateral  is  the  smallest  drain  in  the  system,  and 
discharges  into  a  main  or  sub-main. 

The  Natural  System. — This  is  the  kind  of  drainage 
that  is  first  practised,  and  consists  in  laying  some  lines 
of  tile  in  natural  depressions  which  are  particularly  w^et 
and  troublesome  to  the  agriculturist,  as  represented  in 
Fig.  4.  It  deserves  the  name  of  system  only  because 
in  many  kinds  of  soil  and  localities  it  is  all  that  is  re- 
quired to  make  the  drainage  quite  complete.  It  is  an 
aid  to  natural  drainage,  and  in  fact  completes  it  where 
the  higher  land  naturally  drains  itself  into  adjoining 
depressions.  The  occasional  lines  of  tile  then  put  in 
must  carry  the  drainage  of  the  natural  watershed,  thus 
compelling  the  drains  to  act  as  mains  for  a  considerable 
area.  For  this  reason  more  complaint  is  made  of  the 
incapacity  of  tile  drains  located  in  this  way  than  where 
more    frequent    drainage   is    practised.     The    Natural 


LAND   DRAINAGE    PRACTICE. 


43 


System  is  the  skeleton  which  may  be  developed  into  a 
more  complete  system,  if  afterwards  found  necessary, 
provided  the  size  of  the  drains  is  proportioned  to  the 
area  to  be  finally  improved. 


Fig.  4. — Natural  System. 

The  Grouping  System. — This  may  be  applied  to 
such  land  as  has  basins  or  sloughs,  and  also  areas  of 
dry  land,  or  such  as  it  does  not  seem  desirable  to 
drain.  The  field  is  divided  into  small  drainage  sec- 
tions so  that  one  outlet  will  serve  for  each  division,  and 
a  main  laid  in  the  lowest  land  of  each  separate  drain- 
age basin.  The  drainage  may  be  completed  by  lateral 
lines  converging  toward  the  main  at  such  distances 
apart,  and  having  such  lengths,  as  may  be  adapted  to 
the  purpose.      The  method  is  shown  in  Fig.  5. 

The  Gridiron  System. — This  is  the  old  and  generally 
practised  system  where  thorough  drainage  is  carried 
out.  Systematic  drainage  generally  implies  the  loca- 
tion of  parallel  drains  at  uniform  distances  over  the 
entire  field.  Thorough  drainage ,  however,  is  so  re- 
moving water  from  the  entire  field  as  to  secure  uniform 


44  ENGINEERING   FOR   LAND   DRAINAGE. 

moisture  and  texture  in  all  conditions  of  weather. 
Where  the  soil  is  alike  in  the  tenacity  with  which  it 
holds  moisture  the  system  should  be  uniform,  and 
every  part  of  the  ground  brought  under  the  influence 


Fig.  5. — Grouping  System. 

of  drains  at  regular  intervals.  But  when  the  soil  varies, 
or  the  surface  is  diversified  by  ponds,  sloughs,  and 
draws,  thorough  drainage  means  lines  with  reference  to 
the  different  conditions.  The  gridiron  system  consists 
of  equidistant  parallel  lines  with  mains  and  sub-mains 
for  collecting  and  conducting  the  water  to  some  point 
of  exit.  It  is  economy  to  have  the  laterals  enter  the 
mains  at  right  angles,  but  for  completeness  and  effi- 
ciency they  should  so  enter  that  the  currents  of  the  two 
streams  may  coalesce  and  increase  rather  than  retard 
the  flow  of  the  main.  This  system  is  illustrated  in  Fig.  6. 
Double-main  System. — This  is  applicable  in  broad, 
flat  sloughs  where  it  is   desirable  to  use  two  lines  of 


LAND    DRAINAGE    PRACTICE. 


45 


smaller  tile  instead  of  one  large  main  through  the  cen- 
tre. It  is  sometimes  necessary  to  diverge  the  lines 
toward  the  head,  making  two  systems,  and  running 


Fig.  6. — Gridiron  System. 

laterals  into  each  from  both  sides.  In  draining  hill- 
sides and  wet  slopes  it  is  best  to  lay  lateral  drains  down 
the  slope,  at  such  intervals  as  are  required,  discharging 


Fig.  7. — Double-main  System. 

into  a  collecting-drain.  In  such  cases  have  the  collect- 
ing drain  near  the  base  of  the  slope,  that  the  laterals 
need  not  pass  through  a  flat  bottom,  which  would  re- 


46 


ENGINEERING   FOR    LAND    DRAINAGE. 


tard  the  flow.  But  in  locating  mains  in  this  way  note 
that  unless  the  slough  slopes  but  little  toward  the 
centre  line,  one  centre  main  of  sufficient  capacity  gives 
better  results.  There  are  cases  where  this  system  may 
be  followed  advantageously  both  with  respect  to  cost 
and  efficiency,  while  in  others  it  would  prove  expensive 
and  faulty.      See  Fig.  7. 

Single-line  System. — By  this  is  meant  the  plan  of 
laying  parallel  lines  in  the  direction  of  the  greatest 
slope,  giving  each  a  separate  outlet  into  an  open  ditch 
as  shown  in.  Fig.  8.  This  is  adapted  to  large  areas 
which  have  very  slight  fall  and  where  it  is  consequently 
necessary  to  use  every  inch  of  it  in  grade  and  depth  of 


Fig.  8. — Single-line  System. 

drains,  and  also  to  avoid  the  use  of  excessively  large 
tile  for  mains  which  under  such  circumstances  would 
be  required  if  a  system  involving  mains  and  laterals 
were  used.  A  caution  which  should  be  emphasized  in 
locating  drains  on  level  land  where  grades  must  neces- 
sarily be  very  light  is  to  avoid  overcharging  mains,  a 
thing  that  is  frequently  done  because  the  difference  in 
grades  is  so  often  overlooked. 

These  different  systems,  or   modifications   of  them, 
may  be  used  on  different  tracts,  and  in  various  localities 


LAND    DRAINAGE    PRACTICE.  47 

where  considerations  of  economy  and  efficiency  may 
suggest  their  appropriateness.  It  is  safe  to  say  that 
there  is  no  tract  of  land  requiring  drainage  to  which 
some  of  them  will  not  apply.  Much  will  be  saved  in 
outlay  and  gained  in  efficiency  by  carefully  adapting 
the  system  to  the  particular  tract  to  be  treated. 

Principles  to  be  used  in  Locating  Drains. 

Lay  mains  in  the  line  of  natural  drainage.  There 
are  but  few  tracts  of  land  that  do  not  have  some  natural 
surface  drainage,  or  places  where  the  water  gathers  and 
in  flood-time  flows  off.  It  is  also  true  that,  as  a  rule, 
the  direction  of  the  water  of  the  soil  is  towards  such 
places,  and  in  order  to  intercept  it  and  carry  it  away 
the  main  should  be  located  there.  As  has  been  stated, 
we  must,  if  possible,  work  in  the  line  of  natural  drain- 
age if  we  expect  to  obtain  efficiency  of  work  and  econ- 
omy in  construction.  If  we  consider  the  drainage  of 
some  distant  point  or  tract  without  reference  to  benefit- 
ing land  along  the  line  by  which  it  may  be  reached  by 
a  drain,  then  the  question  hinges  upon  the  difference 
in  cost  of  the  line  by  way  of  some  near  cut,  and  the 
more  circuitous  and  natural  route.  The  shortest  and 
straightest  drain  is  the  best  provided  it  does  the  desired 
work  as  well.  It  is  usually  the  case  that  the  line  of 
natural  drainage  may  be  straightened  by  short  cuts 
here  and  there,  making  the  drain  less  expensive  and 
more  efficient,  without  impairing  its  value  as  a  drain  in 
the  natural  course.  It  should  be  said  in  this  connec- 
tion that  there  are  many  flats,  ponds,  basins,  etc., 
which  can  be  more  economically  reached  by  a  main 


48  ENGINEERING   FOR   LAND   DRAINAGE. 

drain  through  some  short  cut  than  by  the  natural  over- 
flow course.  This  is  a  matter,  however,  that  should 
be  examined  with  care  before  a  location  is  made. 

Direction  of  laterals  with  respect  to  surface  slope. 
—Two  plans  of  arranging  laterals  with  respect  to 
the  surface  slope  are  in  use.  In  comparatively  level 
ground,  the  drains  are  extended  down  whatever  slope 
exists,  as  it  is  desirable  to  obtain  all  the  fall  possible 
for  the  drains. 

On  more  marked  slopes  which  are    traversed  by 
draws  or  depressions,  extending  down  the  slope,  serv- 


F1G.9. — Water-line  between  Drains  when  laid  Diagonally  across  the  Slope. 

ing  to  concentrate  both  surface  and  soil  water,  the 
drains  should  also  pass  down  the  slope  along  the  lines 
of  natural  drainage,  since  the  configuration  of  the  sur- 
face and  the  soil  strata  aid  in  bringing  the  excess  of 
soil  water  to  these  places. 

On  slopes  which  have  no  decided  depressions,  but 
are  comparatively  even  and  smooth,  it  is  often  best  to 
place  the  drains  diagonally  across  the  slope  to  intercept 
a  part  of  the  water  as  it  flows  down,  and  conduct  it 
away  to  a  main  drain.  In  this  plan  each  drain  re- 
ceives nearly  all  of  its  water  from  the  land  lying  on 
the  upper  side  of  it,  so  that  the  water-line  takes  the 
direction  shown  in  Fig.  9.     It  is  not  probable  that  all 


LAND    DRAINAGE   PRACTICE.  49 

of  the  water  in  the  soil  between  any  two  of  the  drains 
is  intercepted  by  the  lower  of  the  two,  but  that  a  por- 
tion passes  under  or  over  it  and  is  intercepted  by  the 
drains  located  on  a  lower  level.  This  across-the-slope 
system  is  adapted  to  seeped  land  lying  at  the  foot  of  a 
slope  which  does  not  itself  require  draining,  as  well  as 
to  wet  hillsides  of  uniform  slope. 

Avoid  short  laterals  where  a  system  can  be  adopted 
in  which  long  parallel  laterals  can  be  used.  This 
is  a  matter  that  has  to  do  with  the  economy  of  the 
work  rather  than  with  its  efficiency.  Every  main  or 
sub-main  will,  of  itself,  drain  the  land  for.  a  certain 
distance  on  either  side  of  it.  All  laterals,  in  order  to 
reach  these  mains,  must  be  laid  through  the  belt  of  land 
thus  drained,  and  hence  a  part  of  each  lateral  will  be 
useless  except  to  conduct  the  water  to  its  receiving 
drain.  The  fewer  junctions  there  are  in  a  given  tract 
the  less  waste  of  length  of  lateral  drains  will  be  there. 
There  are  localities  where,  on  account  of  the  contour 
of  land,  the  short  laterals  are  necessary. 

Make  the  lines  as  straight  as  practicable,  and 
change  direction  by  easy  curves.  Drains  cannot 
always  be  made  straight  from  one  end  to  the  other, 
yet  short  serpentine  crooks  should  always  be  avoided. 
Tangents  may  be  run  and  connected  by  good  curves 
which  will  admit  of  the  drain  being  put  in  the  proper 
place  and  accomplish  the  work  far  better  than  can  be 
done  by  irregular  crooked  lines  which  usually  mark  the 
small  watercourse.  The  disadvantages  of  a  crooked 
line  are  that  the  tiles  are  laid  with  greater  difficulty  and 
more  imperfectly,  there  is  a  loss  of  grade  where  it  is 
needed,  the  frictipn  of  the  running  stream  against  the 
walls  of  the  drain  is  greater  than  in  straight  lines,  and 


50  ENGINEERING   FOR    LAND    DRAINAGE.      • 

a  greater  length  of  drain  will  be  required  to  accomplish 
the  same  purpose. 

Bring  all  land  which  is  deficient  in  natural  drain- 
age under  the  influence  of  tile  drains.  This  requires 
the  investigation  of  the  entire  watershed  for  the  pur- 
pose of  determining  how  complete  the  natural  drainage 
is.  The  engineer  should  adopt  in  his  own  mind  some 
standard  of  the  degree  of  thoroughness  with  which  he 
proposes  to  drain  a  given  tract,  and  locate  his  drains 
with  reference  to  the  natural  wetness  of  the  land.  He 
should  find  out  whether  the  water  comes  from  the  sur- 
face of  some  adjoining  higher  land,  or  from  distant 
springs,  or  is  seep- water  from  slopes.  If  parts  of  the 
field  are  naturally  dry,  or  as  dry  as  it  is  proposed  to 
make  the  other  parts,  he  should  pass  it  by  and  put 
drains  in  the  wetter  portions  so  as  to  bring  them  up  to 
the  standard.  It  may  be  remarked  that  portions  of 
land  which  are  supposed  to  have  sufficient  natural  drain- 
age have  afterward  been  found  deficient  in  this  respect, 
when  compared  with  the  land  that  is  thoroughly  tiled. 

Data  Required  for  Locating  Drains. 

The  knowledge  of  a  piece  of  land  which  is  necessary 
for  the  proper  laying  out  of  a  drainage  system  may  be 
obtained  in  one  of  two  ways  or  partly  by  both. 

First,  the  engineer  may,  by  carefully  inspecting  the 
land  with  the  aid  of  some  one  who  is  familiar  with  both 
surface  and  soil  peculiarities,  determine  upon  the  proper 
system  and  mark  out  the  lines  readily.  There  is  a 
feature  connected  with  the  location  that  is  gratifying  to 
the  engineer,  which  is  that,  when  the  correct  and  nat- 


LAND    DRAINAGE    PRACTICE.  gl 

ural  plan  for  locating  has  been  hit  upon,  the  whole  sys- 
tem may  be  developed  with  ease. 

Secondy  more  or  less  work  with  a  levelling  instrument 
may  be  required  in  order  to  obtain  the  facts  necessary 
for  determining  upon  the  best  plan  of  work.  The 
slopes  may  be  so  slight,  or  so  deceptive  to  the  eye,  and 
the  lines  of  natural  drainage  and  best  points  of  outlet 
so  obscure,  that  it  will  require  an  instrumental  survey 
to  determine  them.  This  involves  a  certain  class  of 
topographical  work  which  will  be  described  hereafter. 

After  the  lines  have  been  located  upon  the  ground, 
or,  more  properly  speaking,  the  general  plan  of  work 
has  been  decided  upon,  then  their  location  in  the  ground 
as  to  depth  and  grade  must  be  done  with  the  lev^el,  if 
any  degree  of  accuracy  in  the  construction  of  drains  is 
expected  to  be  attained.  This  part  of  the  work  will  be 
described  in  another  chapter. 


CHAPTER    IV. 
LEVELLING   AND   TOPOGRAPHY. 

Levelling. 

Levelling  is  the  art  of  finding  how  much  one  point 
IS  higher  or  lower  than  another. 

A  Level  Line  is  one  which  is  perpendicular  to  the 
direction  of  gravity.  A  Levelling  Instrument  is  any  in- 
strument by  which  a  level  line  can  be  accurately  deter- 
mined. 

A  Datum  Plane,  or  "■  Datum,"  is  the  initial  plane  or 
point  in  the  plane  from  which  all  heights  or  elevations 
are  computed. 

The  Elevation  of  a  point  is  its  height  when  referred 
to  datum,  or  its  vertical  distance  above  or  below  datum. 

A  Levelling-rod  is  a  graduated  staff  for  measuring 
the  distance  from  the  line  indicated  by  the  instrument 
to  the  point  whose  elevation  is  desired.  A  Target  Rod 
has  a  sliding  disc  which  is  moved  by  the  rodman  to  the 
position  indicated  by  the  man  at  the  instrument.  The 
rodman  is  expected  to  call  off  the  reading  of  the  figures 
as  indicated  by  the  position  of  the  disc.  A  Speaking- 
rod  is  one  graduated  with  such  distinctness  that  it  can 
be  read  by  the  instrument  man  with  precision.  The 
speaking  rod  is  preferable  for  use  in  all  drainage  work. 

52 


LEVELLING   AND   TOPOGRAPHY.  53 

Bench-marks  are  permanent  objects  whose  eleva- 
tions are  determined  and  recorded  for  future  reference. 

Levelling  Instruments. 

The  engineer's  spirit-level  in  some  of  its  more  or 
less  expensive  forms  is  the  most  accurate  instrument 
and  the  one  with  which  the  most  rapid  work  can  be 
done.  Telescope-levels  are  sufficiently  low  in  price, 
so  that  it  is  not  wise  to  use  the  poor  and  cheap  kind  of 
levels  which  are  recommended  by  many  as  sufficiently 
accurate  for  drainage  purposes,  especially  where  the 
work  to  be  done  is  of  any  magnitude.  The  fact  that 
most  of  our  drainage  work  requires  the  utmost  accuracy 
attainable  is  not  appreciated  by  many.  The  care  and 
adjustment  of  the  instrument  should  be  learned  and  can 
usually  be  done  with  the  aid  of  little  manuals  which  the 
instrument-makers  furnish.  Some  of  the  levels  have  a 
graduated  circle,  by  means  of  which  horizontal  angles 
can  be  measured  and  made  use  of  in  platting  the  lines 
along  which  levels  are  taken.  For  this  work,  however, 
a  compass  either  attached  or  separate  from  the  level  is 
much  to  be  preferred. 

The  rod  is  a  necessary  companion  to  the  level. 
There  is  a  great  variety  of  forms,  each  one  having  its 
advocates.  Some  form  of  the  speaking-rod  or  self-read- 
ing rod  is  to  be  preferred  to  any  form  of  the  target  rod 
for  the  work  herein  described.  It  is  capable  of  being 
used  more  rapidly,  it  makes  the  levelman  more  inde- 
pendent of  his  rodman  because  he  takes  his  own  read- 
ings, and  in  making  cross-sections  it  can  be  used  instead 
of  a  tape-line.  The  divisions  and  colors  should  be  so 
displayed  as  to  be  clearly  seen  and  easily  read.     For 


S4 


ENGlNEEkING  FOR  LAND  DRAINAGE. 


ease  of  computation,  the  decimal  scale  of  feet  and 
tenths  is  best,  though  some  prefer  to  use  feet  and 
inches. 

Fig.  lo  shows  a  form  of  rod  which  has  been  found 
convenient  and  serviceable  for  drainage  surveys,  and 
one  which  can  be  readily  and  cheaply 
made.  It  is  made  of  a  strip  of  straight- 
grained  white  pine,  I  inch  thick,  2  J  inches 
wide,  and  lO  feet  long.  The  ends  are 
shod  with  i-inch  iron  to  protect  them 
from  battering.  The  rod  is  cut  in  two  in 
the  middle  and  a  good  strap  hinge  set  in 
even  with  the  face,  so  that  the  rod  can  be 
folded  together  for  convenience  in  trans- 
portation. It  is  fastened  open  while  in 
use  by  a  rib  of  wood,  which  is  screwed  fast 
to  the  back,  and  covers  the  joint,  and  has 
a  movable  bolt  and  thumb-nut  for  use  in 
holding  the  rod  open  or  shut  as  desired. 
The  accompanying  cut  shows  the  manner 
of  graduating  it.  The  dark  spaces  show- 
ing tenths  of  a  foot  are  red  on  the  rod. 
The  foot  figures  are  large  and  are  painted 
red.  The  tenth  figures  are  black,  and  the 
small  squares  along  the  centre  line  are  also 
black.  There  are  two  hundredth  spaces, 
and  may  be  divided  by  the  eye  so  that 
the  rod  reads  to  single  hundredths  of  a 
foot.  The  variety  and  combination  of  colors  are  such 
as  to  be  clearly  read  at  a  distance  of  from  three  hun- 
dred to  five  hundred  feet,  according  to  light  and  power 
of  the  glass. 


Fig.  io.— Self- 
reading  Rod. 


LEVELLING    AND    TOPOGRAPHY.  55 

The  chain  for  measuring  horizontal  distances  is  also 
necessary  in  making  level  results  available.  The 
100-foot  steel  chain  is  perhaps  the  most  convenient 
and  serviceable  for  drainage  surveys.  It  is,  however, 
open  to  the  objection  that  it  is  not  often  correct  in  length, 
and  hence  should  be  compared  frequently  with  some 
standard.  The  band  chain  should  be  kept  on  hand  for 
accurate  measurements  and  for  testing  the  link  chain, 
but  its  liability  to  be  broken  in  the  hands  of  ordinary 
workmen,  as  well  as  the  disadvantage  of  requiring  two 
hands  for  setting  a  pin  at  the  fore  end,  makes  it  less 
desirable  than  the  link  chain,  from  which  pins  are  set 
from  the  ends  of  the  handles.  The  link  chain  holds 
its  place  in  weeds  and  grass  better  than  the  tape,  can 
be  easily  thrown  across  a  stream,  and  is  more  conve- 
nient for  running  in  curves. 

Two  or  more  flag-poles,  steel  pointed  at  one  end, 
and  each  bearing  a  flag  of  cloth  half  white  and  half 
red,  about  8  in.  by  12  in,  in  size  are  needed  for  mark- 
ing out  courses  for  the  chainmen  to  follow  in  staking 
out  the  lines. 

A  small  hand  ax  for  driving  the  stakes  and  a  hand 
basket  for  carrying  them  completes  the  outfit.  A  set 
of  steel  marking-pins  will  often  be  found  convenient. 

Taking  Levels. 

In  order  to  make  the  process  of  levelling  as  simple 
as  possible  from  beginning  to  end,  and  also  keep  the 
results  in  the  best  form  for  use,  some  method  of  pro- 
cedure and  of  keeping  notes  should  be  adopted  that 
will  be  general  and  apply  to  all  cases  that  the  drainage 


56 


ENGINEERING  FOR  LAND  DRAINAGE. 


engineer  will  have  to  deal  with.  There  is  a  variety  of 
forms  for  keeping  level  notes,  as  well  as  methods  of 
making  drainage  computations,  but  the  methods  here 
described  and  recommended  are  in  quite  general  use 
among  engineers  and  possess  the  merit  of  being  simple 
and  adapted  to  all  kinds  of  work  coming  within  the 
sphere  of  levelling. 

The  Field-book. — A  good  form  and  size  for  a  book 
in  which  to  record  and  keep  the  level  notes  is  one  with 
pages  about  4  inches  by  6J  inches  containing  about 
eighty-five  leaves.      Rule  the  left-hand  page  into  five 


Fig.  II. — Levelling. 

columns,  and  head  them  as  shown  in  level  notes  ac- 
companying Fig.  1 1 .  The  right-hand  page  will  be 
left  for  entering  diagrams  and  explanatory  notes.  A 
size  larger  than  this  is  unnecessary  and  will  also  be 
found  inconvenient  to  carry  in  the  pocket. 

Level  Practice. — Select  some  bench-mark  or  other 
point  from  which  it  is  proposed  to  start,  and  if  its  ele- 
vation has  not  been  determined  before,  assume  one 
which  will  be  convenient  to  use  without  introducing 
minus  expressions.  If  we  begin  low  down  on  some 
water-course,  perhaps  10. 00  will  do;  if  higher  up  20.00, 
30.00,  or  100.00  should  be  used  as  the  elevation  of  the 


LEVELLING   AND    TOPOGRAPHY.  57 

starting-point.  Call  this  point  A  and  write  its  eleva- 
tion in  the  elevation  column  opposite  station  A.  (See 
Fig.  II,  and  the  notes  to  accompany  the  figure,  both 
being  used  to  illustrate  level  practice.)  Set  the  level 
up  midway  between  this  point  and  the  next  point  B 
whose  elevation  is  to  be  obtained.  Have  the  rodman 
hold  his  rod  at  A ,  taking  care  to  hold  it  vertically,  take 
the  reading  of  the  rod  and  enter  it  in  the  column  of 
Back  Sights  opposite  station  A.  In  the  example  it  is 
5.10.  Add  the  back  sight  to  the  elevation  of  the  point 
A  and  we  have  the  elevation  of  the  line  of  sight  through 
the  instrument  or  the  * '  height  of  instrument, "  as  it  is 
called,  and  indicated  on  the  notes  as  H.I.  This  is 
15.10.     Enter  it  in  the  H.I.  column  opposite  station 

A.  Next  take  a  sight  on  B,  called  a  foresight,  and 
enter  the  reading  in  the  F.S.  column  opposite  station 

B.  This  in  the  example  is  2.80.  Subtract  this  read- 
ing from  1 5. 10,  the  height  of  the  instrument,  and  write 
the  difference,  12.30,  in  the  elevation  column  opposite 
station  B.  This  is  the  height  of  B  with  reference  to 
the  starting-point  A .  If  the  elevation  of  other  points 
is  desired  before  a  change  of  instrument  is  made,  take 
as  many  foresights  as  wanted  and  obtain  the  elevation 
of  the  points  in  the  same  way  as  just  described.  Next 
change  the  Instrument  to  some  point  beyond  By  and 
take  a  back  sight  on  station  B,  Add  this  reading  to 
the  elevation  of  B  to  obtain  the  height  of  the  instru- 
ment in  its  new  position.  Enter  the  sum  in  the  H.I. 
column  opposite  B.  In  the  example  the  back  sight  is 
3.70,  elevation  12.30,  H.L  16.00.  Take  a  foresight 
on  (7  and  subtract  the  reading  from  16.00,  the  H.L,  and 
obtain  13.80,  the  elevation  of  C.      Remove  the  instru- 


58 


ENGINEERING    FOR   LAND    DRAINAGE. 


ment  to  a  point  beyond  d  and  obtain  the  elevation  of 
D  in  the  same  way.  The  points  upon  which  two  read- 
ings are  taken  are  called  turiiing- points.  All  others 
except  bench-marks  are  called  intermediates.  Pegs 
should  be  driven  upon  which  to  make  turning-points. 
These  are  frequently  called  **hubs  "  in  practice.  By 
carefully  observing  the  figure  here  given,  and  compar- 
ing it  with  its  accompanying  notes,  the  routine  of  simple 
levelling  can  be  clearly  comprehended  by  the  reader. 
The  column  of  elevations  shows  at  a  glance  the  com- 
parative height  of  every  point  taken  with  reference  to 
the  datum  used. 

It  will  now  be  urfderstood  how  levelling  is  simply 
finding  how  much  higher  or  lower  one  point  is  than 
another.  To  insure  correct  results  the  instrument 
should  be  in  good  adjustment,  rod  readings  should  be 
taken  correctly  and  entered  accurately  in  the  notes,  the 
book  work  should  be  correctly  carried  out,  and  not  the 
least  important  matter  to  be  observed  is  that  the  in- 
strument should  be  set  about  equally  distant  from  both 
turning-points. 

The  notes  may  be  proved,  first  by  reviewing  carefully 
all  of  the  additions  and  subtractions,  and  second  by 
adding  the  column  of  foresights  and  the  column  of  back 
sights.  Take  the  difference  of  these  sums,  and  if  it 
equals  the  difference  of  the  elevations  of  the  points  com- 
pared, the  work  on  the  book  is  correct. 

LEVEL  NOTES  TO  ACCOMPANY  FIG.  11. 


Sta. 

BS. 

H.I. 

F.S. 

Elev. 

A 

B 

C 

D 

S.io 
3-70 
5-40 

IS- 10 
16.00 
19.20 

10.00 
12.30 
13.80 
14-95 

2.80 
2.20 
4.25 

LEVELLING   AND    TOPOGRAPHY.  59 

Proof :    Difference     of    elevation    between    A     and 
D  =  14.95  —  10.00  =  4.95. 

Sum  of  back  sights  =14.20 
Sum  of  foresights     =     9.25 


Difference  of  elevation  =    4.95 

Drainage   Topography. 

Drainage  surveys  involve  the  collection  and  repre- 
sentation of  such  facts  relating  to  the  surface  of  the 
land,  its  soil  and  subsoil,  as  will  be  of  service  in  de- 
termining upon  and  carrying  out  a  plan  for  the  profit- 
able drainage  of  the  land  so  examined.  It  is  a  branch 
of  work  that  comes  within  the  special  province  of  the 
drainage  engineer,  and  it  must  be  done  with  greater 
or  less  thoroughness  before  he  can  plan  a  drainage  pro- 
ject with  any  assurance  that  it  will  accomplish  the  de- 
sired work  when  carried  out. 

The  completeness  of  a  drainage  survey  must  be  meas- 
ured by  the  time  and  money  that  can  be  devoted  to 
it,  and  by  the  thoroughness  of  the  drainage  work  for 
which  the  survey  is  made.  There  should  be  an  adap- 
tation of  these  factors  to  the  result  aimed  at.  The  en- 
gineer should  understand  what  data  and  information  are 
required,  and  then  make  his  plans  to  obtain  them  in 
the  most  systematic  and  expeditious  manner  possible, 
otherwise  he  will  fritter  away  his  time  and  energy  upon 
matters  that  do  not  pertain  to  the  case  in  hand.  A 
survey  may  be  required  of  a  field,  farm,  district,  town- 
ship, or  county,  yet  in  all  cases  the  work  must  be  con- 
ducted so  as  to  cover  the  points  that  will  be  required 


6o  ENGINEERING    FOR   LAND    DRAINAGE. 

within  the  limits  of  the  allotted  time  and  expense. 
Every  thorough-going  engineer  takes  pride  in  making 
his  work  as  complete  as  possible,  even  at  the  expense 
•af  using  more  time  and  labor  than  he  may  be  paid  for. 

The  Preliminary  Survey, 

The  preliminary  survey  or  reconnoissance  consists  in 
making  a  personal  examination  of  the  ground  with 
reference  to  its  general  features  or  geography,  using  for 
this  purpose  any  surveys  or  maps  that  can  be  obtained 
and  information  that  can  be  gathered  from  residents 
and  others  who  may  be  acquainted  with  the  land.  It 
should  include  an  examination  of  the  water-courses 
and  ditches,  where  their  source  is,  and  where  they  dis- 
charge. The  kind  of  soil  may  often  be  read  from  the 
character  of  the  vegetation.  The  object  of  this  **  re- 
viewing "  is  to  determine  the  practicability  of  some  pro- 
pDsed  drainage  scheme,  or  to  plan  for  a  more  complete 
survey  of  the  field  or  tract.  If  it  is  simply  a  field,  a 
few  levels  may  be  taken,  and  the  water-shed  lines  be 
determined,  when  the  engineer  can  at  once  make  his 
plans  and  proceed  with  the  location  work.  This  is  the 
simplest  form  of  outline  survey  and  is  applicable  only 
to  fields  whose  drainage  Hmits  and  slopes  are  easily 
determined  or  in  the  case  of  extended  tracts,  for  the 
purpose  of  planning  for  a  more  complete  survey. 

There  are  several  methods  of  making  a  more  detailed 
survey,  and  the  value  of  each  will  depend  upon  the 
nature  of  the  tract  and  the  object  sought  by  the  sur- 
vey. The  following  are  some  of  the  plans  which  are 
adapted  to  this  class  qf  work. 


LEVELLING   AND   TOPOGRAPHY.  6l 


With  Boundary  Line  as  a  Base. 

Having  the  boundary  lines  of  the  tract,  go  to  the 
supposed  lowest  point  and  establish  a  bench  from  which 
to  level.  Run  a  line  of  levels  on  or  near  the  boundary 
of  the  tract,  taking  elevations  of  the  highest  and  lowest 
points,  important  ditches,  ponds,  etc.  It  will  be  best 
to  measure  the  distances,  setting  hubs  at  every  500  or 
600  feet  and  note  all  points  at  which  levels  are  taken 
by  the  distance  they  are  from  the  initial  point.  All 
elevations  should  be  referred  to  the  initial  bench,  which 
for  convenience  may  be  recorded  as  100.  From  any 
station  on  this  boundary,  base  lines  can  be  run  to  the 
interior  and  any  desired  point  can  be  located  and  its 
elevation  taken,  or  interior  cross  lines  can  be  run  from 
which  the  topography  can  be  made  up.  During  this 
operation  the  engineer  should  keep  his  eyes  open  to 
every  peculiarity  of  the  land  over  which  he  passes.  He 
should  keep  running  notes  in  his  mind  and  make  en- 
tries in  his  book  of  observations  that  may  be  of  use  to 
him  in  making  up  his  topography. 

For  a  survey  of  this  kind,  and  in  fact  for  any  method 
used  in  topographical  surveys,  the  rodman  should  be 
efficient  and  expeditious,  thus  leaving  the  man  at  the 
instrument  free  to  give  his  entire  attention  to  his  proper 
work  without  being  harassed  by  a  blundering  rodman. 
Care  should  be  taken  to  use  every  possible  check  on 
the  levels  so  that  the  engineer  may  be  confident  in  the 
end  that  they  are  correct. 


62  ENGIXEERIXG   FOR   LAND   DRAINAGE. 


Water-cvurse  as  a  Base. 

A  second  method  especially  applicable  to  district 
work  is  to  use  the  main  water-course  as  a  base  and  re- 
fer all  other  lines  to  it.  In  this  case  the  line  should  be 
measured,  stakes  set  at  the  angles  and  levels  taken. 
Ordinates  may  be  run  from  this  line  and  in  such  direc- 
tions as  the  judgment  of  the  engineer  may  dictate. 
The  object  is  the  same  in  either  case,  viz.,  to  get  the 
course  and  slope  of  the  natural  depressions,  to  find  the 
water-shed  lines  and  the  area  of  the  drainage-basLa. 

Method  by  Central  Base  Line. 

Many  tracts  of  land  have  such  irregular  boundaries, 
with  no  well-defined  outlet  stream  or  other  prominent 
features,  that  the  methods  previously  given  for  making 
a  preliminary  survey  will  not  be  as  easy  of  application 
as  the  one  to  be  described.  Run  a  central  base  line 
through  the  longest  dimension  of  the  field  or  plantation, 
setting  stakes  and  solid  hubs  at  distances  of  400  feet. 
(See  Fig.  12.)  These  are  to  be  used  as  permanent 
stations  in  all  subsequent  work  of  a  preliminary  nature, 
and  the  line  should  be  described  from  a  compass  bear- 
ing. Levels  should  be  taken  upon  each  hub  and  used 
as  bench-marks.  All  of  the  low  and  high  points  may 
now  be  sought  out  by  inspection  or  with  the  aid  of  the 
level  and  marked  by  a  stake  and  hub.  Find  elevation 
of  these  points.  Take  a  compass  bearing  and  measure 
the  distance  from  these  points  to  the  nearest  station 
on  the  base  line,  or  if  a  circle  without  compass  needle 
is  used,  set  up  at  the  nearest   station   and  turn  off  the 


LEVELLING   AND   TOPOGRAPHY 


63 


angle  from  base  line  to  the  new  points.  Each  one  may 
now  be  used  as  a  station  in  planning  and  locating  the 
drains  immediately  surrounding  it.     The  data  taken  in 


Fig.  12.  —Topography  from  Central  Base  Line. 

this  work  should  be  sufficient  to  plat  the  drainage  sys- 
tem correctly,  or  if  only  preliminary  levels  are  desired 
the  field  points  can  be  platted.  As  many  points  may 
be  located  and  levelled  as  may  be  necessary  to  plat  the 


64  ENGINEERING   FOR   LAND   DRAINAGE. 

topography  of  the  ground  or  to  locate  needed  drains. 
It  is  better  to  keep  this  work  platted  up  every  day,  for 
while  the  notes  are  fresh  in  the  mind,  quicker  and  bet- 
ter work  can  be  done  in  mapping  than  if  the  notes 
alone  must  be  relied  upon.  While  the  notes  may  and 
ought  to  be  quite  full,  the  memory  enlivens  the  view 
and  enables  one  to  add  that  to  the  descriptive  map 
which  will  be  of  value.  If  there  should  be  no  plat  of 
the  tract,  the  boundary  should  be  run  in  with  the  com- 
pass if  it  is  desired  to  have  a  complete  map  in  every 
detail.  All  maps  should  be  made  carefully  to  a  scale, 
the  practical  value  of  which  will  appear  when  it  is  de- 
sired to  make  estimates  from  them  for  further  work. 


Record  of  the   Work, 

The  engineer  now  wishes  to  put  his  work  on  record 
so  that  he  can  plan  future  location  surveys  intelligently 
or  represent  the  capabilities  of  the  tract  plainly  to 
others,  which  latter  consideration  is  very  important. 
For  this  purpose  the  plat  should  be  transferred  from 
the  field-book  and  drawn  to  a  convenient  scale  upon  a 
sheet  of  paper  and  the  necessary  items  entered.  Re- 
cord the  elevations  directly  upon  the  map  at  the  loca- 
tion where  the  levels  were  taken.  Indicate  water- 
courses, ponds,  trees,  etc.,  by  conventional  signs. 
(Fig.  23.)  Sketch  in  dividing  lines  on  water-sheds  and 
indicate  surface  slopes  by  arrows.  Designate  each 
drainage-basin  which  has  a  distinctive  outlet  as  a  drain- 
age section  by  the  letters  A,  B,  C,  etc. 

The  work  thus  far  done  forms  a  geography  of  the 
tract  which  shows  its  natural  drainage  slopes.     The 


LEVELLING   AND   TOPOGRAPHY.  65 

elevation  numbers  show  the  actual  fall  from  one  point 
to  another.  The  engineer  can  now  compute  the  area 
of  each  drainage  section.  The  topography  is  plain  to 
every  one  who  may  have  occasion  to  examine  the  map. 
It  fits  the  ground  so  that  most  of  the  points  can  be 
relocated  from  the  map  by  their  relation  to  natural  ob- 
jects and  established  features.  An  approximate  esti- 
mate of  the  cost  of  drainage  can  be  made  from  this 
map,  though  in  order  to  arrive  at  an  accurate  estimate, 
drain  lines  should  all  be  measured. 


Topography  by  Contour  Lines. 

Contour  lines  are  drawn  upon  a  map  defining  points 
on  the  surface  of  the  land  which  have  the  same  eleva- 
tion. The  vertical  distances  between  these  lines  may 
be  taken  at  6  inches,  i  foot,  or  2  feet,  or  any  other  de- 
sirable distance,  in  which  case  the  number  of  the  con- 
tour lines  show  to  the  eye  at  once  the  elevation  of  the 
ground  over  which  the  line  passes.  The  line  of  great- 
est slope  of  the  land  will,  of  course,  be  directly  across 
the  contour  lines. 

For  the  purpose  of  illustration,  suppose  it  is  desired 
to  make  a  survey  and  map  of  a  farm  from  which  a  plan 
for  its  drainage  is  to  be  made  and  in  time  executed. 
The  earlier  in  the  work  such  a  map  can  be  made,  the 
greater  will  be  its  value.  Especially  will  such  a  map 
be  of  service  if  the  projected  work  is  to  be  done  at  dif- 
ferent times  as  facilities  or  means  may  permit. 

The  Survey. — Begin  at  one  corner  of  the  farm  or 
field  whose  adjacent  sides  are  straight  lines  and   use 


66  ENGINEERING    FOR    LAND    DRAINAGE. 

these  two  sides  as  bases  from  which  to  work.  Have 
'stakes  prepared  which  should  be  about  i6  inches  long. 
Common  lath  are  good  for  this  purpose.  Begin  at  the 
corner  and  measure  off  a  base,  setting  a  stake  at  each 
station  of  lOO  feet.  Letter  the  stake  at  the  corner  A 
and  the  others  B,  Cy  D,  etc.,  in  order.  This  is  the  base 
line.  Begin  at  the  point  A  and  measure  from  that 
point  along  the  adjacent  side  of  the  field,  and  number 
these  stakes  i,  2,  3,  etc.,  until  the  limit  of  the  field  is 
reached.  The  last  stake  should  record  the  length  of 
the  line  in  feet. 

Set  a  flag  1 00  feet  from  the  last  stake  at  a  right  angle 
with  the  line  run,  so  that  a  line  can  be  run  parallel  with 
the  first.  Begin  at  the  stake  B  on  the  base  line  and 
measure  a  line  and  set  stakes  parallel  to  the  first  line. 
Proceed  in  the  same  way  across  the  entire  farm  until 
it  is  entirely  checked  into  squares  of  100  feet.  In  lay- 
ing off  these  lines,  they  should  be  kept  straight  by 
means  of  flags,  which  are  set  ahead  of  the  work,  and  in 
case  a  prominent  feature,  such  as  a  centre  of  a  pond  or 
a  stream  is  crossed,  an  intermediate  stake  should  be  set 
and  properly  numbered.  These  lines  can  now  be  de- 
scribed as  ^,  B,  C,  etc.,  lines,  and  any  point  on  that 
line  by  the  number  of  the  stake  on  it. 

The  next  work  is  to  '  *  book  ' '  the  farm  or  field,  as  the 
case  may  be.  For  convenience  it  will  be  best  to  select 
the  lowest  point  on  the  farm  as  a  datum  if  it  is  ap- 
parent to  the  eye.  If  not  establish  a  **  bench-mark  " 
and  assume  a  datum  plane  at  the  initial  point  or  A  of 
the  base  line.  Take  each  line  in  order  and  take  a 
level  at  each  stake,  recording  the  elevation  of  the  sur- 
face under  its  proper  head.      The  headings  of  the  level 


LEVELLING   AND   TOPOGRAPHY.  6j 

pages  would  read  ''Levels  on  Line  A,"  *♦  Levels  on 
Line  B,"  etc. 

The  stations  at  which  levels  are  taken  should  be  num- 
bered as  they  are  on  the  stakes.  Additional  natural 
features  of  the  surface  should  be  noted  on  the  book  in 
connection  with  the  elevation  of  the  stations.  When 
the  whole  farm  has  thus  been  gone  over,  the  level  book 
will  show  the  elevation  of  the  ground  at  the  position 
of  every  stake  that  has  been  set,  which  forms  the  data 
from  which  a  map  is  to  be  made. 

Practical  Hints. — Before  leaving  the  description  of 
the  field  work  several  practical  hints  will  not  come 
amiss.  The  staking  may  be  done  by  two  active  young 
men,  one  at  each  end  of  a  steel  band  chain,  if  it  is 
preferred.  The  head  chainman  carries  the  stakes  in  a 
hand  basket  and  sticks  one  at  the  end  of  the  chain,  the 
rear  chainman  lining  him  in  by  a  flag-pole,  which  has 
been  previously  set  at  the  proper  place.  The  rear  chain- 
man  numbers  the  stake  properly  and  drives  it  with  a 
hatchet.  The  stakes  at  the  boundary  of  the  farm  should 
be  permanent  ones  and  remain  in  position  so  that  the 
points  in  the  interior  can  be  produced  at  anytime  desired. 

When  the  levelling  is  being  done,  two  lines  may  be 
taken  at  one  setting,  and  upon  completing  the  first  two 
lines  the  next  two  may  be  taken  from  the  upper  end 
back  toward  the  base  line,  provided  care  be  taken  to 
keep  the  notes  in  order  so  that  each  station  shall  have 
its  proper  elevation  recorded  against  it. 

*  *  Bench-marks  ' '  should  be  established  at  convenient 
places  for  future  reference.  "■  Turning-points  "  should 
be  taken  on  pegs,  but  other  levels  may  be  taken  from 
the  ground  surface. 


68  ENGINEERING   FOR    LAND    DRAINAGE. 

The  work  should  be  done  at  a  time  when  growing 
crops  will  not  interfere  with  running  the  lines. 

It  would  appear  upon  first  considering  work  like  this, 
especially  to  one  who  has  not  tried  it,  that  obtaining 
the  data  before  described  would  involve  considerable 
time  and  labor.  It  may  be  said,  however,  that  1 60 
acres  of  ordinary  prairie  farming  land  may  be  surveyed 
as  above  described — two  chainmen  with  stakes,  fol- 
lowed by  levelman  and  rodman — in  two  days. 

The  Map. — All  necessary  information  is  now  in  tab- 
ular form  on  the  field-book.  Make  a  map  of  the  farm 
by  first  adopting  a  scale  and  platting  the  boundary 
lines  according  to  notes  and  measurements  taken  in  the 
field  and  recorded  in  the  book.  One  half  inch  to  100 
feet  is  a  good  scale  to  use  for  a  farm  of  160  acres. 
Reproduce  the  lines  laid  off  in  the  field  so  that  the 
plat  will-  correctly  represent  the  field  on  the  scale 
adopted    and  used.     (Fig.  13.) 

Now  write  the  elevations  as  found  in  the  field-book 
at  the  intersections  of  the  lines  on  the  plat,  which  in- 
tersections represent  the  position  of  the  stakes  which 
were  set  in  the  field. 

The  plat  now  shows  the  comparative  elevations  of 
these  points  over  the  entire  farm,  and  also  such  other 
features  as  may  have  been  noted  in  making  the  survey. 
The  contour  lines  may  now  be  drawn  from  the  eleva- 
tions which  are  shown.  The  vertical  distance  between 
them  may  be  any  unit  it  may  be  convenient  to  adopt. 
In  the  example  here  given,  the  distance  is  one  tenth  of 
a  foot.  They  are  numbered  in  order  of  elevation. 
The  plat  now  shows  at  a  glance  the  degree  and  direc- 
tion of  slope  of  any  part  of  the  tract.     The  elevation 


LEVELLING    AND   TOPOGRAPHY. 


69 


figures    need   not  be  retained   after  the   contours  are 
sketched  in  and  numbered. 


13.5  13.2  13.0  12.7  12.6  12.5        ^12.4  12.2         12.0  11.9  12,0 


ii.r 


Fig.   13 — Topography  by  Contours.     Squares  lOO  feet,  Level  Datum 
10  feet.     Interval  between  Contour  Lines  -^^  foot. 

This  method  of  representing  topography  is  so  com- 
plete that  a  plan  for  drainage  may  be  accurately  laid 


70  ENGINEERING    FOR    LAND    DRAINAGE. 

upon  the  contour  map.  The  contours  show  points  of 
equal  elevation  over  the  entire  field  in  such  a  way  that 
the  surface  slope  is  shown  to  the  eye  at  a  glance. 
However,  for  ordinary  drainage  work  the  topography 
of  a  field  may  be  found  in  sufficient  detail  by  methods 
previously  described  which  require  less  labor.  A 
knowledge  of  the  elevation  and  location  of  the  high 
and  low  points  in  a  field  or  district  is  usually  sufficient 
for  the  effective  planning  of  a  drainage  system. 


CHAPTER   V. 
LAYING  OUT  DRAINS  IN  THE  FIELD. 

Staking  Out  Drains. 

One  or  more  lines  of  drains,  or  an  entire  system  hav- 
ing been  determined- upon,  the  next  work  is  to  stake  out 
the  lines  and  prepare  them  for  the  construction  of  the 
drains.  Stakes  should  be  prepared  beforehand.  A 
good  material  for  stakes  is  what  is  known  as  fence  lath. 
They  are  4  feet  long,  \\  inches  wide,  and  f  inch  thick. 
They  may  be  cut  in  three  pieces,  making  them  16 
inches  long,  which  is  a  suitable  length  for  land  which 
is  reasonably  free  from  grass  and  heavy  weeds,  but 
ordinarily  they  should  be  2  feet  long.  These  are 
called  guides,  and  serve  to  carry  the  necessary  figures 
and  to  show  the  location  of  the  grade  stakes.  An 
equal  number  of  grade  stakes  should  be  made  to  ac- 
company them.  They  may  be  of  the  same  material, 
but  only  I  foot  long.  Prepare  as  many  sets  of  these 
as  there  are  stations  of  100  feet  to  measure  off,  with 
some  extras  for  intermediates.  Where  the  work  of 
making  the  ditches  is  to  be  done  without  much  delay, 
common  plastering  lath,  which  are  more  easily  carried, 
may  be  used  for  guideso 

Begin  with  a  main  drain,  first  flagging  out  the  course 
SO  that  the  stakes  may  be  lined  in  straight.     Set  the 

71 


;2 


ENGINEERING  FOR   LAND   DRAINAGE. 


first  stake  near  the  outlet  of  the  main  and  about  14 
inches  to  the  right  of  the  centre  of  the  proposed  drain. 
Drive  the  grade  stake  to  the  surface  of  the  ground,  and 
the  guide  stake  about  4  inches  beyond  it,  as  shown 
in  Fig.  14.  Let  the  fore  chainman  hold  the  forward 
handle  of  the  chain  and  a  guide  stake  in  a  vertical  posi- 


FiG.  14. — Guide-stakes  and  Hubs. 

tion  in  the  same  hand,  and  let  the  rear  chainman,  with 
the  handle  of  the  chain  at  the  grade  stake  and  his  eye 
directly  over  it,  line  him  in  with  the  flag  which  marks 
the  position  of  the  line  to  be  staked  out.  The  fore 
chainman  sticks  the  stake  where  directed  and  drops  a 
grade  stake  by  it.  He  then  pulls  ahead  another 
length  of  the  chain  and  is  again  put  into  line.  The 
rear  chainman  drives  the  stakes  and  marks  them  with 
a  large  lead-pencil  in  order,  calling  the  first  stake  o 
and  the  next  I,  etc.,  for  all  full  stations  from  outlet  to 
the  upper  end  of  the  drain. 

Where  curves  are  made,  intermediate  stakes  should 
be  set  in  such  a  way  that  they  can  be  followed  and 
used  in  digging  the  ditch,  and  should  be  marked  so  as 
to  indicate  the  number  of  feet  from  the  outlet  up  to  each 


LAYING  OUT   DRAINS   IN  THE   FIELD.  73 

Stake.  As  for  example,  between  stations  5  and  6  curve 
stakes  are  set  20  feet  apart.  They  would  be  marked 
5.20,  5.40,  5.60,  etc.,  and  indicate  5^2^  stations,  or 
520  feet,  etc. 

Another  thing  to  be  noted  at  the  time  of  staking  the 
main  is  where  the  sub-mains  and  branches  enter.  If 
it  is  desired  that  a  branch  line  should  join  the  main 
between  stations,  a  stake  should  be  set  as  an  interme- 
diate with  the  character  o  upon  it  and  also  the  name  of 
the  drain  that  enters. 

The  same  plan  of  staking  out  lines  of  all  kinds  should 
be  followed.  Begin  at  the  junction  stake,  and  set  and 
number  the  stakes  from  the  o  or  junction  point  upward 
until  the  upper  end  is  reached.  The  stake  at  the  upper 
end  of  each  drain  should  have  its  respective  name  upon 
it  in  addition  to  the  station  number,  so  that  in  looking 
over  the  system  the  drains  can  be  followed  from  either 
end  by  schedule  or  map. 

Designating  Drains, 

Some  system  of  designating  drains  is  needed  where 
there  are  many  of  them  in  a  system,  in  order  that  the 
notes  may  be  kept  without  confusion  and  also  corre- 
spond with  the  schedule  and  plat  which  should  be 
made  after  the  work  is  laid  out. 

Mains  may  be  designated  as  main  A^  main  B^  etc., 
in  the  order  of  their  size  or  importance.  Branches  of 
each  main  may  be  numbered  in  order,  from  the  outlet 
of  the  main  up,  as  No.  i,  No.  2,  etc.  If  one  of  these 
branches  is  a  sub-main,  that  is,  one  receiving  laterals, 
the  laterals  may  be  designated  as  ^,  by  Cy  of  that  sub- 


74  ENGINEERING   FOR   LAND   DRAINAGE. 

main.  All  numbering  and  lettering  of  drains  is  done 
from  the  outlet  toward  the  upper  ends.  If  this  system 
is  not  followed,  some  other  equally  clear  one  should 
be  used,  so  that  the  engineer  may  avoid  .the  possibility 
of  applying  the  notes  of  one  drain  to  some  other  to 
which  they  do  not  belong.  When  the  whole  arrange- 
ment is  made  clear,  the  contractor  may  take  the  work, 
and  without  any  further  explanation  than  that  which 
appears  in  the  field  and  the  schedules,  he  may  follow 
out  the  work  in  all  its  details. 

Levelling  Drains  and  Keeping  the  Notes, 

The  method  of  taking  the  levels  after  the  drains  are 
staked  out  is  the  same  as  that  previously  described. 
The  rodman  should  hold  the  rod  in  a  perpendicular 
position  upon  each  grade  stake  in  order  beginning,  at 
o  stake,  and  after  the  '  *  all-right ' '  signal  from  the 
levelman,  he  should  at  once  pass  to  the  next  stake 
and  '  *  rod  up  ' '  for  another  reading.  He  should  call 
off  the  station  numbers  of  all  intermediate  stations, 
branches,  etc.,  as  he  approaches  them  that  the  level- 
man  may  enter  them  correctly  upon  his  book.  It 
should  be  remembered  that  in  this  kind  of  work  each 
level  should  be  taken  with  the  same  care.  Every  stake 
must  be  worked  from  in  digging  the  ditch  with  equal 
care.  Sights  of  400  feet  in  length  should  be  regarded 
as  about  the  limit,  though  longer  ones  can  be  taken 
with  reasonable  accuracy.  The  levelman  should  see 
that  his  instrument  is  all  right  at  the  time  he  reads  the 
rod,  and  he  should  keep  his  mind  closely  upon  the  work 
or  he  will  take  incorrect  readings  or  enter  them  incor- 
rectly upon  his  boojkt- 


LAYING   OUT   DRAINS   IN   THE   FIELD.  75 

The  field-book  should  have  two  more  columns  ruled 
in  addition  to  those  described  for  simple  levelling,  one 
for  the  elevation  of  grade  line  or  simply  **  grade  line,'* 
(C.L.)  and  one  for  the  depth  of  cut  at  each  station 
marked  **  Cut."  These  latter  columns  are  for  compu- 
tations to  be  made  after  the  field  work  has  been  com- 
pleted. The  accompanying  specimen  page  of  a  field- 
book  gives  an  example  of  entries  made  in  the  field  and 
the  subsequent  computations  for  a  short  drain. 

A  sketch  plat  of  the  lines  should  be  made  on  the 
right-hand  page.  This  is  very  convenient  and  may  with 
proper  care  be  made  quite  accurate  by  means  of  meas- 
urements taken  to  certain  landmarks  or  permanent 
objects  and  by  sketching  in  the  angles  and  curves. 
All  of  this  can  be  done  at  the  time  of  levelling  without 
retarding  the  work  to  any  extent.  Be  particular  to 
note  where  branch  lines  of  whatever  kind  enter  other 
drains. 

Notes  for  Platting, 

These  should  be  taken  at  the  same  time  the  levelling 
is  done  and  recorded  on  the  right-hand  page  of  the 
notes  if  it  is  expected  that  a  plat  better  than  the  one 
which  can  be  made  from  the  sketch  will  be  required. 
If  done  with  a  compass,  locate  all  outlets  of  drains  with 
reference  to  some  corner  of  the  farm  most  prominent 
or  convenient  by  means  of  a  measurement  and  bearing 
from  it.  Take  the  bearings  of  the  straight  lines  of  the 
ditch,  and  if  a  long  curve  is  made,  of  several  parts  of 
the  curve  so  that  it  may  be  represented  with  reasonable 
accuracy.  Note  where  fence  lines  are  crossed,  and 
make  measurements  from  convenient  stations  to  bound- 


76 


ENGINEERING  FOR   LAND   DRAINAGE. 


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LAYING   OUT   DRAINS   IN   THE   FIELD.  77 

ary  lines  of  the  field  or  farm  in  order  to  check  the  work 
in  drawing  the  plat  or  map.  If  a  level  with  an  attached 
compass  is  used,  these  notes  can  be  taken  with  little 
additional  effort  and  time,  as  use  of  the  compass  can  be 
easily  acquired.  The  compass  gives  all  angles  referred 
to  the  magnetic  meridian  for  that  place,  which  fact 
makes  the  work  more  expeditious  than  any  other  known 
method.  If  done  with  ari  instrument  having  only  a 
graduated  circle^  some  line  of  the  field  or  farm  must 
be  taken  as  a  base,  and  the  angle  which  the  first 
straight  line  of  the  drain  makes  with  it  be  measured. 
Then  the  angles  which  the  several  tangents  of  the 
drain  make  one  with  the  other  should  be  measured, 
being  careful  to  record  whether  these  angles  are  right 
or  left.  The  same  methods  of  checking  by  measure- 
ments as  the  chaining  is  done  should  be  observed  as 
those  described  for  compass  work. 

A  Common  Datum. 

Every  drain  in  the  system  should  have  distinct  notes 
by  itself  similar  to  the  example  given  above  for  illus- 
tration. All  elevations  should  be  referred  to  the  same 
datum,  so  that  the  difference  of  any  two  elevation  num- 
bers anywhere  in  the  system  will  show  the  actual  differ- 
ence of  elevation  of  the  land.  In  other  words,  the 
levels  should  all  be  connected.  This  can  readily,  be 
done  by  observing  this  simple  rule.  When  levelling  is 
begun  on  any  new  line  or  branch  take  the  first  back 
sight  on  some  point  whose  elevation  is  recorded  and  add 
it  to  the  elevation  of  that  point  for  a  new  height  of 
instrument. 


78 


ENGINEERING   FOR   LAND   DRAINAGE. 


The  Profile. 

A  profile  represents  a  vertical  section  of  the  line  of 
survey.  The  level  notes  are  platted  on  profile  paper 
on  which  the  vertical  and  horizontal  scales  are  different 
to  render  irregularities  of  surface  more  distinct  through 
exaggeration.  The  method  of  profiling  the  level  notes 
is  shown  in  Fig.  15.      In  this  diagram,  one  space,  hori- 


WlOOft^ 


234.56789        10       U 
Fig.  15.— Profile  of  Main  A.     (See  Notes.) 


zontal  scale,  equals  50  feet,  and  one  small  space,  ver- 
tical scale,  equals  .2  foot  of  elevation,  which  are  con-- 
venient  scales  in  making  profiles  for  drainage  work.  A 
profile  represents  the  surface  line  correctly  and  should 
be  employed  in  fixing  upon  a  grade  line  when  the  work 
to  be  done  is  of  any  considerable  magnitude. 

To  determine  a  grade,  draw  a  thread  over  the  profile, 
adjusting  it  to  certain  points  of  maximum  and  minimum 
grade,  until  a  desirable  grade  line  is  represented  by  the 
thread.  Transfer  the  elevation  of  points  where  changes 
of  grade  occur  to  the  corresponding  points  on  the 
notes,    and  compute  the  cuts  for  each  station.     The 


LAYING   OUT    DRAINS   IN   THE   FIELD.  79 

profile  represents  the  approximate  relation  of  surface  to 
grade  line,  but  does  not  indicate  the  cuts  at  each  sta- 
tion sufficiently  close  for  use  in  detail  construction. 
Every  profile  should  have  a  name  or  heading  by  means 
of  which  it  can  be  connected  with  the  notes  from  which 
it  has  been  made,  or  with  the  surveyed  line  on  the 
ground  which  it  represents  in  section.  Profile  paper 
used  for  this  work  is  sold  by  houses  dealing  in  engineers* 
supplies. 

Compass  Surveying  for  Drainage  Work, 

The  data  for  platting  farm  and  field  lines,  locating 
preliminary  level  points  for  topographical  work,  drain 
lines,  etc.,  can  be  most  rapidly  obtained  by  use  of  the 
compass.  A  level  equipped  with  a  small  compass  suit- 
able for  field  work  is  convenient  and  very  serviceable. 
The  needle  indicates  the  magnetic  meridian,  an  ap- 
proximately north  and  south  line.  The  true  meridian 
is  a  true  north  and  south  line,  which  if  produced  would 
pass  through  the  poles  of  the  earth. 

The  compass  circle  (Fig.  16)  is  divided  into  degrees 
and  fractions  of  a  degree.  The  letter  E. ,  denoting  east, 
is  at  the  left  hand,  and  W.,  denoting  west,  at  the  right 
hand  of  the  box,  which  is  contrary  to  the  position  of 
these  letters  in  the  small  pocket  compasses.  This 
arrangement  is  necessary  because  in  using  the  field  com- 
pass the  box  is  turned  so  that  the  sights  point  in  the 
direction  of  the  line  whose  azimuth  is  to  be  obtained. 
The  north  end  of  the  needle  is  read,  which  gives  direct 
the  azimuth  of  the  line  or  the  angle  which  it  makes 
with  the  magnetic  meridian. 


So 


ENGINEERING  FOR  LAND  DRAINAGE. 


The  bearijig  of  a  line  is  the  angle  which  it  makes 
with  the  direction  of  the  magnetic  needle.  The  length 
of  a  line  with  its  bearing  is  termed  its  course.  To 
take  the  bearings  of  a  line,  set  the  compass  directly- 
over  a  point  in  it  at  one  extremity  if  possible,  though 
this  is  not  essential..  Bring  the  compass  to  a  level 
position.     Have  a  flag  or  rod  set  on  another  point  of 


Fig.  i6. — Taking  Compass  Bearings. 

the  line.  Direct  the  sights  upon  this  rod  as  near  the 
bottom  as  possible.  Always  keep  the  north  end  of 
thci  compass  ahead.  It  is  distinguished  from  the 
south  end  by  some  conspicuous  mark  on  the  face. 
Sight  accurately  to  the  flag  and  read  the  north  end  of 
the  needle.  To  do  this,  note  first  whether  the  N.  or 
S.  point  of  the  compass  is  nearest  the  north  end  of  the 
needle,  second,  the  number  of  degrees  to  which  it 
points,  and  third,  the  letter  E.  or  W.  nearest  the  north 
end  of  the  needle.  Always  read  and  record  bearings 
in  this  order. 


LAYING   OUT   DRAINS   IN   THE   FIELD.  8 1 

In  the  figure  the  line  is  AB  along  which  the  sights 
point.  The  needle  points  constantly  to  the  meridian, 
hence  in  turning  the  sights  to  the  line  AB  the  angle 
NB  is  turned  off,  or  from  o""  to  35°,  and  the  needle 
reads  north  35°  east,  hence  the  bearing  of  the  line  is 
N.  35°  E. 

To  test  the  accuracy  of  the  bearing  set  up  the  instru- 
ment at  the  opposite  end  of  the  line  and  take  a  back 
sight  upon  the  first  point.  If  the  reading  agrees  with 
the  first,  but  with  opposite  letters,  the  bearing  first 
taken  was  correct.  The  declination  of  the  needle  is  the 
angle  which  the  magnetic  meridian  and  the  true  merid- 
ian make  with  each  other.  There  is  always  a  declina- 
tion to  take  into  account  except  on  or  near  a  certain 
line  passing  across  the  country  called  the  line  of  no  va- 
riation. The  declination  of  the  needle  is  constantly 
changing.  It  is  desirable  to  record  lines  with  their  true 
bearings,  or  as  nearly  so  as  practicable,  though  this 
feature  of  the  work  does  not  possess  the  importance 
which  is  attached  to  it  where  surveys  are  made  for  the 
definition  and  determination  of  land  lines.  The  local 
declination  can  be  determined  by  setting  up  the  com- 
pass upon  an  old  land  line  whose  bearing  is  known  if 
such  can  be  found,  or  in  the  absence  of  such  a  line  a 
bearing  may  be  taken  upon  the  pole  star  and  declina- 
tion noted.  This  will  be  only  approximate,  as  the  star 
is  i^  degrees  from  the  pole,  revolving  about  it,  and 
being  on  the  true  meridian  only  twice  in  twenty-four 
hours. 

Another  method  of  determining  an  approximately 
true  meridian  is  by  equal  shadows  of  the  sun. 

On  the  south  side  of  a  level  surface,  as  at  5  in  Fig. 


82 


ENGINEERING   FOR    LAND   DRAINAGE. 


i/j  place  an  upright  staff  not  less  than  lO  feet  long. 
Two  or  three  hours  before  noon  mark  the  extremity  A 
of  its  shadow.  Describe  an  arc  of  a  circle  with  5  the 
foot  of  the  staff  for  centre  and  SA  the  distance  to  the 
extremity  of  the  shadow  for  radius.     About  as  many 


Fig.  17. — Obtaining  Meridian  by  Equal  Shadows  of  the  Sun. 

hours  after  noon  as  it  had  been  before  noon  when  the 
first  mark  was  made,  watch  for  the  moment  when  the 
end  of  the  shadow  touches  the  arc  at  another  point  B. 
Bisect  the  arc  AB  at  N.  Draw  SN  and  it  will  be 
the  true  north  and  south  line.  Set  up  the  compass  at 
Sj  sight  on  iV^or  5iV^  produced  and  read  the  needle. 
The  reading  will  be  the  declination  of  the  needle  at 
that  place.  It  is  more  important,  however,  to  record 
on  the  notes  the  declination  used  than  it  is  to  go  into 
the  niceties  of  obtaining  and  using  an  absolutely  correct 
declination  angle  for  hne  work  of  the  character  herein 
described. 

If  the  compass  has  a  variation  plate,  set  off  the  dec- 
lination assumed  or  determined  and  record  all  bearings 
as  read.     If  there  is  no  such  provision  for  mechanically 


LAYING   OUT   DRAINS   IN   THE    FIELD.  83 

correcting  the  azimuth,  make  corrections  on  the  notes 
according  to  the  following  rule. 

To  Reduce  Magnetic  Bearings  to  True  Bearings. 

When  the  variation  is  east,  as  in  Western  and  South- 
ern States,  for  bearings  N.  and  W.  or  S.  and  E.  sub- 
tract declination  from  magnetic  bearing.  For  bearings 
N.  and  E.  or  S.  and  W.  add  declination  to  magnetic 
bearing. 

When  the  variation  is  west,  as  in  the  Northeastern 
States,  for  bearings  N.  and  W.  or  S.  and  E.  add  dec- 
lination. 

For  bearings  N.  and  E.  or  S.  and  W.  subtract  dec- 
lination. 

Now  that  wire  fences  and  other  improvements  made 
of  iron  and  steel  are  in  such  common  use,  care  must  be 
taken  to  keep  the  compass  distant  from  all  iron  and 
steel,  which  of  course  will  deflect  the  needle  and  destroy 
the  reliability  of  its  readings.  Should  it  be  necessary 
to  obtain  the  bearing  of  wire  fence  line,  an  offset  of 
30  feet  may  be  made  and  the  bearing  of  the  parallel 
line  be  read. 

Keeping  Compass  Notes. 

The  running  form  of  keeping  notes  is  simple  and  in 
common  use.  For  example,  in  recording  the  notes  of 
drains,  the  following  running  notes  may  be  written  on 
the  right-hand  page  of  the  level-book. 

DRAIN  NO.  2. 

Sta.  oto    6 N.  10°  30' E. 

««    6  to    8 N.    4°  00'  E. 

"    8  to  15 N.  32°  00'  W. 

««  15  to  22  (end) N.  15°  20'  W. 


S4 


ENGINEERING   FOR   LAND  DRAINAGE. 


If  certain  points  for  mapping  or  topography  are  to 
be  located  from  some  station,  the  following  tabulated 
form  may  be  employed: 

OBSERVATIONS  AT  PRELIMINARY  STATION  NO    6 


Sta. 

Bearings. 

Distance 
Feet. 

Remarks. 

Sta   No.  6  to 
A  .. 

N.  42"  30'  E 
8.   70°  20'  W 
S.  60°  00'  w. 
N.  20°  30'  W 

800 

1000 

600 

800 

Low  swale 

C 

Walnut-tree 

D 

Upper  end  ditch  to  horse  pond. 
Highest  point  in  west  field 

E  ..    . 

The  same  form  may  be  used  to  record  a  continuous 
and  connected  line  like  the  boundary  of  a  farm  or  field. 

Back  sights  should  be  taken  at  each  station  to  ascer- 
tain if  there  are  any  disturbing  influences  which  cause 
the  needle  to  read  differently  at  the  two  ends  of  the 
line.  If  a  discrepancy  in  the  two  readings  is  found, 
some  point  on  the  same  line  intermediate  between  the 
two  should  be  used  to  determine  which  of  the  bearings 
is  correct. 

The  instructions  thus  far  given  are  sufficient  to  sug- 
gest to  the  beginner  the  method  of  doing  simple  line 
work  with  the  compass.  With  a  little  practice  in  the 
field,  without  which  no  one  can  understand  the  subject 
fully,  a  novice  may  soon  acquire  all  needed  proficiency. 


CHAPTER   VI. 
FIXING  THE  GRADE  OF  DRAINS. 

A  grade  line  as  determined  by  a  survey  is  the  line 
along  which  the  water  of  the  drain,  when  constructed, 
is  to  flow. 

Fall  is  the  common  term  for  slope  of  surface  when 
applied  to  land,  and  for  total  head  when  applied  to 
drains. 

The  available  fall  is  the  fall  that  can  be  given  to 
a  drain  in  a  prescribed  distance,  as  distinguished  from 
the  fall  of  the  land  through  which  the  drain  extends. 

The  grade  of  a  drain  is  its  rate  of  fall  and  is  ex- 
pressed in  inches,  or  in  decimals  of  a  foot,  per  lOO  feet. 
When  expressed  in  decimals  of  a  foot  per  lOO  the 
grade  is  said  to  be  so  much  per  cent. 

Determining  the  grades  upon  which  the  drains  should 
be  laid  requires  much  skill  and  knowledge  of  practical 
details  of  construction,  together  with  the  understanding 
of  the  requirements  of  the  soil,  capacity,  cost,  and 
efficiency  of  various  kinds  and  sizes  of  drains,  some  of 
which  subjects  will  be  discussed  in  subsequent  chapters 
of  this  work.  The  minimum  grade  that  may  be  suc- 
cessfully used  for  the  tile  drains  is  a  matter  of  great 
moment  where  level  lands  are  treated,  and  will  de- 
pend much  upon  the  accuracy  with  which  the  drains 
will  be  constructed.     The  topography  of  the  surface 

85 


S6  ENGINEERING   FOR   LAND   DRAINAGE. 

places  limitation  upon  grades  which  cannot  always  be 
changed  by  artificial  work.  While  grades  of  2,  3,  or  4 
inches  per  ICX)  feet  may  be  desired  as  a  minimum,  they 
cannot  be  obtained  in  ver>*  many  tracts  of  land  which 
may  be  successfully  drained.  Grades  as  low  as  ^  inch 
per  ICX)  feet  are  in  successful  operation,  giving  good 
results  on  thousands  of  acres  of  land.  Mains  laid  for  a 
distance  on  a  level  are  sometimes  used  with  success, 
the  flow  through  such  mains  depending  upon  the  head 
given  by  the  fi-ee  water  in  loose  soils,  and  by  lateral 
drains  ha\'ing  a  grade  greater  than  that  of  the  main. 
The  lack  of  fall  must  be  offset  by  increased  size  of 
drains,  and  by  the  greatest  degree  of  accuracy  in  their 
construction. 

A  uniform  grade  is  the  simplest.  Having  decided 
upon  the  depth  of  drain  at  the  outlet  and  also  at  the 
upp)er  end,  as  for  instance  3  feet,  subtract  this  from 
the  elevation  of  each  of  these  points  and  obtain  the 
elevation  of  the  grade  line  at  the  outlet  and  upper  end 
respectively.  The  difference .  of  the  elevation  is  the 
available  fall,  which,  divided  by  the  number  of  stations, 
gives  the  fall  per  station. 

Starting  with  the  elevation  of  the  grade  line  at  the 
outlet,  add  the  grade  p>er  station  to  this  elevation  to 
obtain  the  elevation  of  the  grade  line  for  the  next  suc- 
ceeding one,  and  so  continue  to  add  the  increments. 
For  intermediate  stations  use  a  projxjrtional  part  of  the 
grade  per  station. 

The  cut  or  depth  of  drain  is  found  by  taking  the  dif- 
ference beti^'een  grade  and  surface  elevations.  The 
last  column  of  figures  under  the  head  *  *  Cut ' '  is  the  ob- 
ject sought,  and  is  that  for  which  all  other  work  so  far 


FIXING   THE   GRADE   OF   DRAINS.  8/ 

has  been  done.  The  cut  measured  from  the  top  of  the 
grade  pegs  and  connected  by  a  line  will  give  a  true 
and  uniform  grade  from  beginning  to  end. 

A  change  of  grade  is  frequently  necessary  where  the 
land  has  any  considerable  slope,  otherwise  the  drains 
will  be  too  deep  or  too  shallow  in  places  for  economy 
in  digging  or  for  efficiency  of  operation.  This  is 
effected  by  dividing  the  lines  into  the  necessary  di- 
visions, each  division  having  a  grade  of  its  own.  The 
station  where  the  change  of  grade  is  made  should  be 
noted  on  the  book.  In  the  example  of  the  notes  given 
the  grade  is  .25  per  100  as  far  as  station  4,  and  then 
changes  to  .20  per  100.  Where  a  cut  is  to  be  made 
through  a  ridge  to  reach  a  flat  which  it  is  desired  to 
drain,  determine  the  least  depth  of  drain  that  should 
be  used  at  the  upper  end,  take  a  safe  grade,  say  .10 
per  100,  or  .20  per  100,  and  run  down  by  subtracting 
the  grade  from  the  elevation  of  each  station  in  order, 
until  the  ridge  is  passed  and  the  desired  depth  is 
obtained,  then  change  to  a  heavier  grade.  It  is  the 
ordinary  method  of  grading  a  drain  reversed. 

A  large  number  of  examples  might  be  given,  but  the 
above  are  sufficient  to  show  the  beginner  the  general 
plan  of  work.  A  few  examples  of  his  own  worked  out 
will  soon  give  him  an  insight  into  the  practical  details 
of  grades. 

When  a  sub-main  or  lateral  enters  another  drain  it 
IS  best  to  have  an  outfall  from  the  branch  line  into  the 
main.  This  is  commonly  called  a  **  drop  "  and  should 
be  proportionate  to  the  size  of  the  tile  used  on  both 
lines.  For  example,  branches  into  a  6-inch  main 
should  drop  .20,  into  an   8-inch  .30,  10- inch  .40,  12- 


88 


ENGINEERING   FOR    LAND    DRAINAGE. 


inch  .50.  To  compute  this,  add  the  drop  to  the  ele- 
vation of  grade  Hne  at  the  point  of  junction,  which  will 
give  elevation  of  starting-point  of  branch.  Example : 
At  station  4.50  of  notes,  Branch  No.  i  is  to  have  a 
drop  of  .20.  The  grade  hne  98.35  -|- .20  =  98.55 
:=  elevation    of   grade    line    at    outlet   branch.      This 


Fig.  18. — Angle  and  Drop  for  Tile  Drain. 


should  be  transferred  to  the  notes  of  Branch    No.    i 
and  used  as  the  initial  point  for  computing  the  grade 
of  that  line.      If  short  bends  or  curves  are  necessary  a 
little  additional  grade  should  be  allowed,  provided  it . 
can  be  had. 

The  depth  at  which  it  is  desired  to  lay  the  drains 
will  often  have  much  to  do  with  the  determination  of 
the  grades.  No  inflexible  rule  can  be  given,  but  uni- 
formity should  as  much  as  possible  be  secured.  If  the 
flow  in  drains  is  alternately  slow  and  rapid  and  then 
stands  still,  the  tile  being  full  at  one  place  and  half 
full  at  others,  the  efficiency  of  the  drain  is  only  part  of 
what  it  might  be  were  the  grades  carefully  arranged 
and  the  size  of  the  tile  proportioned  to  them.  A  care- 
ful survey  and  corresponding  adjusted  grade  will  often 


U  N  I  V  E  R  f. 
FIXING   THE   GRADE   OF   DRAINS. 


89 


add  one  half  to  the  efficiency  of  a  drain,  as  compared 
with  one  which  is  carelessly  made. 

For  convenience  in  reducing  the  *'  Cut  "  column  of 
the  notes  to  feet,  inches,  and  fractions  of  an  inch,  which 
will  usually  be  demanded  by  workmen  in  digging  a 
ditch,  a  table  is  here  appended.  In  all  engineering 
computations  it  is  desirable  to  use  the  decimal  scale, 
but  the  engineer  will  soon  learn  the  equivalents  of  deci- 
mals of  a  foot  in  inches  and  fractions  so  that  he  can 
write  them  without  referring  to  the  table.  Reductions 
given  to  the  nearest  J  inch  are  sufficiently  close  for 
practice. 

Table  1. 

DECIMALS  OF  A  FOOT  REDUCED  TO  INCHES. 


Foot. 

Ins. 

Foot. 

Ins. 

Foot. 

.0104 

i 

.2188 

2f 

.4271 

.0208 

.2292 

1 

.4375 

.0313 

.2396 

•  4479 

.0417 

.  2500 

3 

.4583 

.0521 

.2604 

.4688 

.0625 

.2708 

^ 

•4792 

.'0729 

■ 

.2813 

f 

.4896 

.0833 

I 

.2917 

^ 

.5000 

.0938 

.3021 

1^ 

.5104 

.1042 

.3125 

1 

.5208 

.1146 

.3229 

.5313 

.1250 

.3333 

4 

.5417 

•  1354 

•  3438 

•  5521 

.1458 

.3542 

•  5625 

.1503 

■ 

.3646 

.5729 

.1667 

2 

•  3750 

.5833 

.1771 

•  3854 

.5938 

.1875 

.3958 

i 

.6042 

.1979 

.4063 

.6146 

.2083 

* 

.4167 

5 

.6250 

Ins. 

Foot. 

Ins. 

Foot. 

5* 

•  6354 

7f 

.8438 

.6458 

.8542 

.6563 

i 

.8646 

. 

.6667 

8 

.8750 

.6771 

1 

.8854 

• 

.6875 

.8958 

.6979 

f 

.  9063 

6 

.7083 

1[ 

.9167 

^ 

.7188 

'f 

.9271 

^ 

.7292 

1^ 

.9375 

1 

-7396 

•i" 

.9479 

4 

.7500 

9 

.9583 

f 

.7604 

.9688 

1 

.7708 

X 

•  9792 

.7813 

1 

.9896 

7 

.7917 

i 

1 .00 

.8021 

4 

.8125 

1 

.8229 

.8333 

10 

Ins. 


i 
* 
i 


Depth  of  Drains. 
The  depth  which  drains  should  be  laid  is  a  matter 
which  has  received  a  great  deal  of  attention  since  the 
time  that  underdrainage  began  to  be  practised.     Ad- 
vocates of  deep  and  shallow  drains  have  very  earnestly 


90  ENGINEERING   FOR   LAND   DRAINAGE. 

argued  their  favorite  theories.  It  is  one  of  those  cases 
in  which  theories  do  not  always  work  out  in  practice, 
the  factor  which  prevents  this  being  the  variations  in 
the  characteristics  of  the  soil  which  is  treated.  In  or- 
der that  any  one  theory  may  prove  correct,  it  must 
be  assumed  that  a  soil  of  a  certain  kind  under  certain 
conditions  is  to  be  operated  upon.  This  kind  of  soil, 
however,  is  not  always  present,  and  the  theory  cannot 
apply  in  full. 

In  speaking  of  depth  of  drainage,  4  feet  is  called  deep 
drainage,  3  feet  medium,  and  2  to  2 J  shallow  drain- 
age. If  drains  are  laid  deep  the  soil  must  be  suscept- 
ible to  the  ready  percolation  of  water,  and  by  this 
process  be  converted  into  a  soil  of  greater  or  less  value 


Fig.  19 — Effect  of  Depth  of  Drains  on  Open  Soils. 

to  plants.  In  Fig.  19  the  difference  in  depth  is  shown 
to  the  eye  with  its  attendant  advantage.  Another  ad- 
vantage is  that  the  soil  has  a  greater  reservoir  capacity 
for  water  which  is  valuable  in  times  of  excessive  rain- 
fall, and  still  another,  the  drains  may  be  varied  in  dis- 
tance apart  upon  the  principle  illustrated  in  Fig.  9. 
Now,  this  is  all  true  for  deep,  permeable,  rich  soils, 
and  with  such  there  is  no  doubt  as  to  the  value  of  gen- 
eral 4-foot  drainage. 

On  the  other  hand,  many  subsoils  at  a  depth  of  4 
feet  have  no  fertility  in   them.      Though   plant  roots 


FIXING   THE   GRADE   OF   DRAINS.  9I 

often  penetrate  them  seeking  moisture,  they  are  quite 
retentive,  so  that  drainage-water  passes  through  them 
slowly.  In  such  cases  drains  of  less  depth  than  4 
feet  are  of  greater  value  for  agricultural  purposes. 
When  the  statement  is  made  that  drains  should  never 
be  laid  as  shallow  as  2  feet,  it  is  confronted  by  the 
fact  that  in  many  localities  where  the  soil  is  exceed- 
ingly retentive,  and  the  subsoil  more  so,  deep  drains 
have  little  immediate  effect.  Not  that  they  are  devoid 
of  value,  or  will  not  in  tinie  prove  beneficial  to  the  soil, 
but  their  value  will  not  be  commensurate  with  their 
cost.  The  more  retentive  the  soil,  the  steeper  will  be 
the  line  of  saturation,  and  the  less  will  be  the  breadth 
of  land  which  will  be  acted  upon  by  each  drain. 

It  may  be  said  that  for  farm  lands,  lateral  drains 
should  be  about  3  feet  deep,  unless  the  compact 
and  retentive  soil  indicates  that  less  depth  should  be 
used.  When  it  is  attempted  to  follow  any  general 
depth  the  necessity  of  obtaining  suitable  grades  for 
the  drains  will  often  make  some  parts  of  the  drain 
deeper  or  shallower  than  desired.  A  nice  and  econom- 
ical adjustment  of  the  depths  of  the  several  drains  of  a 
system  can  be  learned  only  by  practical  work.  A 
practical  knowledge  of  the  field,  coupled  with  the  facts 
on  the  field-book,  form  the  key  to  the  dormant  re- 
sources of  the  soil. 

Frequency  of  Drains, 

This  is  also  a  question  upon  which  there  is  a  wide 
difference  of  opinion  and  a  consequent  difference  of 
practice.     The  science  and  art  of  land  improvement 


92 


ENGINEERING   FOR    LAND   DRAINAGE. 


are  peculiar  in  one  respect,  and  that  is  this :  No  rule  or 
plan  applicable  to  one  locality  will  strictly  apply  to  an- 
other. A  design  for  a  park  in  one  city  will  not  be 
suitable  for  another,  owing  to  varying  natural  features, 
as  well  as  requirements  which  must  be  met.  A  soil 
in  one  locality  will  drain  as  readily  and  perfectly  with 
drains  1 50  feet  apart  as  others  will  with  drains  40  feet 
apart,  and  upon  this  fact  depends  the  distance  apart 
that  drains  should  be  placed.  It  would  be  a  waste  of 
labor  and  material  to  place  drains  40  feet  apart  in 
some  of  our  soils,  while,  on  the  other  hand,  to  place 
drains  at  intervals  of  150  feet  in  some  soils  would 
come  far  short  of  accomplishing  thorough  drainage. 
The  cost  of  the  work  has  much  to  do  with  the  dis- 


FiG.  20. — Drainage  of  a  40-acre  Field  containing 
Pond  with  High  Land  surrounding  it, 

tance  apart  at  which  drains  are    usually  placed,  and 
thorough  drainage  is  often  sacrificed  to  this.     As  ob- 


FIXING   THE   GRADE    OF   DRAINS.  ^3 

served  in  another  chapter,  the  object  of  thorough  drain- 
age is  to  bring  all  the  soil  under  the'  influence  of  drains 
either  natural  or  artificial.  There  are  soils  where  drains 
200  feet  apart  give  good  drainage  for  farm  crops. 
There  are  others  where  33  feet  is  none  to  near  to  lay 
the  drains.  These  conditions  vary  so  widely  that  one 
familiar  with  one  kind  of  soil  is  inclined  to  disbelieve  a 
statement  regarding  the  other.  Here  is  where  the  ex- 
perience and  close  observation  of  the  engineer  come 
into  use  and  should  be  worth  many  dollars  to  the  land- 
owner. It  cannot  be  urged  too  strongly  upon  the  en- 
gineer who  is  entering  upon  this  class  of  work,  to  famil- 
iarize himself  with  that  very  interesting  subject,  the 
behavior  of  soils  under  different  methods  of  treatment 
and  also  acquaint  himself  with  the  physical  differences 
of  soils  with  reference  to  drainage. 

This  is  a  field  for  the  exercise  of  close  observation 
upon  the  ground.  As  a  hint  along  this  line,  it  may 
be  said  that  the  vegetation  is  a  good  index  to  the  nat- 
ural character  and  condition  of  the  soil.  Certain  plants 
grow  luxuriantly  upon  some  kinds  of  soil  and  not  on 
others.  Learn  what  these  are  and  keep  them  in  mind 
when  reviewing  the  land.  There  may  be  some  open 
ditches  of  greater  or  less  magnitude  which  affect  the 
adjoining  land  more  or  less  widely  as  to  its  drainage. 
This  effect  may  be  known  by  the  appearance  of  the 
land  and  vegetation  which  is  found  upon  it.  If  it  is 
the  spring  of  the  year,  dig  a  post-hole  and  note  how 
rapidly  it  fills  with  water.  These  observations  may 
suggest  the  means  by  which  may  be  gained  that  knowl- 
edge of  the  soil  which  is  necessary  to  an  intelligent 
location  of  drains  as  to  depth  and  distance  apart. 


94 


ENGINEERING   FOR   LAND   DRAINAGE. 


Preliminary  Estimate. 

The  following  will  be  useful  in  making  preliminary 
estimates  of  the  number  of  feet  of  drains  which  will  be 
required  per  acre  when  laid  in  parallel  lines  at  the  dis- 
tances apart  indicated : 

20  feet  apart. 2 178  feet 

25  **  ''  .  . 1742  '' 

30  ''  '' 1452  ** 

40  **  **  1089  ** 

50  **  ** 872  ** 

100  **  **  436  ** 

150  **  **  291  ** 

200  *<  **  218  ** 

The  number  of  feet  of  drains  per  acre  as  shown 
above  does  not  include  any  intercepting  main  which 
may  be  necessary  to  make  the  work  complete.  For 
instance,  should  it  be  necessary  to  locate  a  main 
through  the  centre  of  a  field,  its  length  must  be  divided 
by  the  number  of  acres  in  the  field,  and  the  result 
added  to  the  number  which  is  found  in  the  table  above, 
opposite  the  number  in  the  column  indicating  the  dis- 
tance apart  which  it  is  proposed  to  lay  the  drains. 


I 


CHAPTER   VII. 
MAPS  AND  RECORDS. 

The  drains  having  been  staked  out,  the  grades  and 
cuts  figured,  and  the  size  and  number  of  the  tile  fixed 
upon,  a  map  of  the  drains  should  be  made  which  will 
show  their  position,  length,  fall,  size  of  tile,  and  the 
physical  features  of  the  land  through  which  they  pass. 
The  details  of  farm  work  are  usually  executed  upon  the 
ground  so  that  complete  data  is  not  secured  until  the 
work  is  finished. 

A  sketch  map  can  be  readily  made  from  the  notes 
which  were  taken  in  the  field,  and  will  show  quite  ap- 
proximately the  position  of  the  lines,  and  should  be 
made  and  used  as  a  working  map  in  the  distribution  of 
tile  and  in  digging  the  ditches.  A  copy  of  the  depth 
figures  for  each  line,  with  the  working  map,  constitutes 
the  information  which  will  be  necessary  for  any  man 
or  set  of  men  to  construct  the  work  as  laid  out. 

The  finished  map  should  be  made  from  measure- 
ments and  angles  which  were  taken  in  the  field  for  that 
purpose,  and  should  be  drawn  to  a  scale  and  sufficiently 
embellished  to  present  a  creditable  appearance.  The 
young  engineer  who  has  had  no  previous  training  or 
practice  in  this  work  should  not  fail  to  take  up  this 
branch  and  study  to  make  his  maps  and  records  cred- 
itable and  accurate. 

95 


96  ENGINEERING    FOR    LAND    DRAINAGE. 

Drafting  Instruments. 

While  there  are  other  instruments  which  are  some- 
times desirable,  the  following  are  all  that  are  essential 
for  ordinary  work:  A  right-line  pen,  a  scale  divided  to 
tenths  of  an  inch,  a  drawing-board  24  inches  square,  a 
bottle  of  liquid  India  ink,  a  protractor  for  platting 
angles,  a  T  square  with  24-inch  blade,  a  bottle  of  car- 
mine ink,  a  few  thumb-tacks  for  fastening  paper  to  the 
board  and  some  good  steel  pens. 

A  serviceable  paper  for  making  working  plats  is 
what  is  known  as  bond  paper.  The  size  of  sheet  most 
convenient  is  18  inches  by  24  inches.  The  merit  of 
this  paper  is  that  it  is  flexible,  does  not  crack  when 
folded  and  carried  in  the  pocket,  is  partially  transparent, 
so  that  it  can  be  used  in  making  tracings,  and  also 
constitutes  a  fair  negative  from  which  blue  prints 
can  be  made.  Vellum  or  tracing-cloth  is  particularly 
adapted  to  use  in  making  duplicate  copies  where  fine 
blue  prints  are  desired. 

For  finished  maps,  Whatman's  hpt-pressed,  un- 
mounted paper  should  be  used;  sheets  17  X  22  are 
convenient  in  size. 

Platting  Compass  Notes  and  Angles. 

The  platting  of  a  survey  made  with  the  compass  con- 
sists in  drawing  on  paper  the  lines  and  angles  which 
have  been  measured  on  the  ground.  The  lines  should 
be  drawn  to  scale  and  the  angles  measured  with  a  pro- 
tractor. A  protractor  is  a  scale  in  the  form  of  a  semi- 
circle of  brass  or  celluloid  divided  into  180  parts  or 
degrees  and  numbered  in  both  directions.     The  straigfht 


MAPS   AND   RECORDS. 


97 


edge  has  a  mark  in  the  middle  opposite  the  90°  mark 
on  the  circumference. 

To  lay  off  any  angle  at  any  point  place  the  straight 
edge  of  the  protractor  on  the  line  with  the  mark  at  the 
point ;  with  the  point  of  a  sharp  pencil  make  a  mark 
on  the  paper  at  the  required  number  of  degrees  and 
draw  a  line  from  the  mark  to  the  given  point. 

To  plat  compass 
bearings  draw  a  merid- 
ian line  in  light  pencil 
through  the  initial  sta- 
tion or  starting  point, 
place  the  protractor 
upon  the  line  and  point 
as  directed  in  the  pre- 
ceding paragraph,  and 
lay  off  the  angle  called 
for  by  the  notes.  Set  off 
by  scale  the  distance  on 
this  course  to  the  next 
point.  Draw  a  merid- 
ian line  through  the 
point  thus  established 
and  in  the  same  mannei 
plat  the  next  and  fol- 
lowing courses.  Should 
a  field  have  been  sur-  Fig.  21.- 
veyed,    the  last   course 

should  end  at  the  starting-point  and  the  plat  should 
come  together  or  close.  If  it  does  not  close,  it  shows 
that  some  error  has  been  made  either  in  the  field  or  in 
platting  the  work.     The  method  of  using  the  protractor 


-Platting  Compass  Bearings. 


98  ENGINEERING   FOR    LAND   DRAINAGE. 

in  platting  is  shown  in  Fig.  2 1 .  The  semicircle  part 
of  the  protractor  should  be  placed  in  the  direction  of 
the  course  to  be  marked  and  the  angle  read  from  the 
north  end  of  the  protractor  for  all  bearings  beginning 
with  iVand  from  the  south  end  for  bearings  beginning 
with  5. 

Making  the  Map, 

Determine  first  how  large  it  is  desired  to  have  the 
map  and  the  scale  that  can  be  used.  The  measure- 
ments in  the  field  have  been  taken  and  recorded  in 
stations  of  lOO  feet,  so  a  convenient  scale  for  represent- 
ing the  lines  will  be  a  certain  number  of  hundred  feet 
to  one  inch.  The  more  detail  work  it  is  desired  to 
represent  on  the  map  the  larger  should  be  the  scale. 
200  to  300  feet  to  i  inch  are  good  scales  for  farms 
of  moderate  size,  while  for  large  tracts  500  to  1000 
feet  must  be  used  in  order  to  keep  the  size  of  the 
map  within  convenient  limits.  Lay  off  the  boundary 
of  the  farm  or  tract  according  to  the  proposed  scale. 
Locate  the  position  of  the  outlets  of  the  drains  and 
work  upward  in  laying  off  the  lines  in  the  same  man- 
ner and  order  as  the  survey  was  made.  Number  the  sta- 
tions where  angles  occur,  where  branch  drains  enter, 
and  also  the  number  of  the  station  at  the  upper  end  of 
each  drain  line.  All  angles  should  be  laid  off  with  the 
protractor,  and  the  intersection  of  the  drain  lines  with 
field  or  fence  lines,  and  in  large  tracts  with  land  lines, 
should  be  shown.  All  of  this  outline  work  should  be 
done  in  light  pencil  lines,  and  when  completed  re- 
drawn in  ink.  In  working  maps  the  drain  lines  are 
usually  drawn  in  red,  all  others  in  black.     For  a  finely 


MAPS   AND   RECORDS. 


99 


finished   map,    it  is   better  to  indicate  the  drains  by 
broken  black  lines. 


860       880      900 


Scale:  800  ft.=l  inch 

Fig.  22.— Drainage  Plan  for  a  Farm  of  i6o  Acres  of  Level  Land. 

Conventional  Topographical  Signs. — These  are  rep- 
resentations of  some  of  the  leading  features  of  the  land 
by  arbitrary  signs  which  resemble  the  objects  as  we 
look  down  upon  them.  A  sufficient  number. of  these 
should  be  used  to  indicate  to  the  eye  at  a  glance  what 
the  character  of  the  surface  is.  This  representation 
should  be  aided  by  words  of  description  where  full  de- 


lOO 


ENGINEERING   FOR    LAND   DRAINAGE. 


tails  are  desired  to  be  shown.  Peculiarities  of  the  soil 
may  be  indicated  in  this  way  and  thus  useful  facts  be 
recorded.  A  few  of  the  more  common  conventional 
topographical  signs  have  already  been  shown  in  Fig.  2  3 . 


Swamp 


Plow  Land 


urtfc  wSBJ*  »"'^  >»"■*'  ^^'"- 


^wW«, 


Grass 


Pond 


^.    m 


% 


€l 


Orchard 


1  ® 


Railroad 


X  #/ 


Bridge 


Ditch 


^^^-. 


^Woods 


Brush 


Buildings 


Wagon  Road 


Mud 


Fig.  23. — Conventional  Signs  used  to  Represent  Topography. 

Lettering. — The  style  in  which  the  lettering  of  the 
map  is  done  has  a  striking  effect  upon  its  general  ap- 
pearance. When  a  working  map  is  made,  the  letter- 
ing should  be  done  in  some  free-hand  letter  which  can 


MAPS   AND    RECORDS.  lOI 

be  rapidly  made  with  a  writing-pen.  The  points  that 
should  be  aimed  at  in  this  letter  should  be  plainness, 
neatness,  and  such  variety  as  will  give  a  general  air  of 
finish  to  the  work.  Not  very  much  time  can  profitably 
be  given  to  this  part  of  a  working  map,  so  that  neat- 
ness and  despatch  in  making  it  will  be  found  of  great 
advantage  to  the  young  engineer.  The  finished  map 
should  receive  more  careful  attention  in  the  execution 
of  letters,  particular  attention  being  given  to  the  adap- 
tion of  the  style  of  the  letter  to  the  importance  of  tl  e 
thing  for  which  it  stands.  Simple  letters  are  best  for 
drainage  maps,  as  well  as  the  most  easily  made.  They 
should  be  lightly  pencilled  in  until  a  design  is  found 
which  is  adapted  to  the  map,  after  which  they  should 
be  inked  in.  The  letters  should  be  the  last  part  of 
the  map  to  be  finished  and  should  be  so  placed  as  not 
to  obscure  figures  which  accompany  lines. 

Copying  Maps. 

It  is  sometimes  desirable  to  make  one  or  more  copies 
of  a  map,  either  for  use  in  the  construction  of  the 
work  or  for  preservation  with  the  field  notes.  This  is 
most  conveniently  done  upon  tracing-cloth  or  vellum. 
Stretch  the  cloth  over  the  map  and  draw  in  the  lines 
by  letting  the  pen  follow  directly  over  the  lines  on  the 
map.  Instead  of  the  tracing-doth,  a  thin  quality  of 
bond  paper  may  be  used.  This,  however,  is  not  so 
transparent  as  the  cloth  and  hence  requires  a  strong 
light  in  order  that  the  lines  may  be  readily  traced. 

Where  several  duplicates  are  required,  what  is  known 
as  blue  prints  can  be  made  more  cheaply  than  hand 


102  ENGINEERING   FOR   LAND   DRAINAGE. 

tracings.  They  are  made  as  follows:  Make  a  copy  of 
the  map  it  is  desired  to  print  upon  tracing-cloth  or 
upon  a  transparent  paper,  taking  care  to  make  all  of  the 
lines  definite  and  black.  Place  this  copy  with  its  face 
side  against  the  glass  of  the  print  frame.  This  frame 
may  be  made  of  a  strong  picture-frame  of  sufficient 
size  to  take  in  the  drawing.  The  back  should  be  made 
firm  and  so  arranged  that  it  can  be  clamped  closely  to 
the  glass  by  means  of  buttons  attached  to  the  back  of 
the  frame.  Upon  the  drawing  or  map  place  a  piece  of 
the  prepared  paper,  the  prepared  face  against  the  trac- 
ing, and  place  some  smooth  papers  or  layers  of  cloth 
upon  the  back  of  it  and  clamp  the  backing  board  firmly 
against  it,  so  that  every  part  of  the  tracing  will  be 
firmly  pressed  against  the  glass.  The  prepared  paper 
can  be  bought  of  dealers  in  engineers*  supplies.  •  It 
should  be  kept  in  a  dry  and  perfectly  dark  place. 
When  both  tracing  and  paper  have  been  arranged  in 
the  frame  as  above  directed,  expose  the  glass  to  the 
direct  rays  of  the  sun  for  four  or  five  minutes  if  the  sun 
is  bright.  Take  out  the  paper  and  place  it  in  a  bath  of 
clear  water.  Move  the  water  over  it  until  the  paper 
turns  a  clear  blue  and  the  lines  show  a  clear  white. 
Then  hang  up  to  dry.  If  the  blue  is  too  light,  the  ex- 
posure was  too  short ;  if  too  dark,  it  was  out  too  long. 
If  paper  which  is  not  fully  transparent  is  used  as  a 
copy  it  must  be  exposed  longer  than  a  perfectly  trans- 
parent negative.  A  little  practice  will  soon  enable  tiie 
novice  to  make  good  prints. 


CHAPTER  VIII. 

GRADING  THE  DITCHES  FOR  TILE. 

The  engineer  should  be  thoroughly  conversant  with 
practical  tile-laying  and  with  the  best  plans  for  secur- 
ing the  most  accurate  work.  Workmen  can  frequently 
dig  the  ditch,  but  do  not  understand  the  principles  of 
grading  it  accurately  according  to  survey.  Many  work- 
men think  that  it  is  more  difficult  to  do  than  it  is, 
hence  the  engineer  should  seek  to  make  the  whole 
matter  plain.  A  survey  should  be  carefully  worked  to 
or  its  full  value  cannot  be  realized.  There  are  two 
good  plans  for  grading  a  tile  ditch,  both  of  which  de- 
pend upon  the  same  principle  and  both  simple  and 
practical. 

The  Line  Method. — This  consists  of  setting  a  line  or 

wire  directly  over  the  grade  stakes  at  a  given  distance 

above  and  parallel  to  the  bottom  of  the  proposed  ditch. 

As  the  bottom  is  finished  for  the  tile  it  is  tested  by 

means  of  a  gauge  which  carries  a  light  crossbar  set  at  a 

right  angle  to  it.      The  line  is  stretched  parallel  to  the 

grade  line  of  the  ditch  and   5   feet  above  it,  which  is 

a  convenient  height,  and  tested  by  the  gauge  which  is 

5  feet  long  from  the  bottom  to  crossbar.      The    line 

should  be  supported  at  two  or  three  points  between 

stations  to  prevent  sagging. 

103 


104 


ENGINEERING   FOR    LAND    DRAINAGE. 


To  set  the  line,  subtract  the  depth  of  the  ditch  at  a 
given  station  from  the  length  of  the  gauge  to  be  used 
and  set  the  line  above  the  grade  stake  the  amount  of 
this  difference.  Then  the  distance  below  the  hub  plus 
the  distance  above  it  to  the  line  equals  the  length  of 
gauge.     This  plan  is  illustrated  in  Fig.  24. 


Fig.  24. — Grading  by  Gauge  and  Line. 

Another  method  of  finding  the  point  at  which  to  set 
the  line  does  away  with  all  mental  subtraction  of  fig- 
ures and  the  errors  which  may  arise  from  it.  Take  a 
stick  the  length  of  the  proposed  gauge, — in  the  above 
case  5  feet, — and  graduate  it  to  inches  and  quarter- 
inches,  beginning  at  the  top  and  numbering  down. 
One-eighth  inches  can  be  obtained  by  estimation.  To 
use  the  measure  at  any  grade  peg,  note  the  cut  or 
depth  for  that  stake,  find  the  same  mark  on  the  meas- 
ure, set  the  bottom  end  of  the  measure  upon  the  grade 
peg  and  bring  the  line  to  this  point.  When  the  meas- 
ure is  placed  upon  any  grade  stake,  the  position  for  the 
line  is  at  the  mark  corresponding  to  the  depth  mark  at 
that  stake. 

The  Target  Method. — Another  method  of  grading 
called  the  target  plan  is  better  for  large  and  deep 
ditches,  and  is  in  favor  with  many  workmen  for  grad- 


A  FOUR-INCH   LATERAL   DRAIN. 


(  To  /ace  page  1 04 . ) 


GRADING   THE    DITCHES   FOR    TILE. 


105 


ing  all  kinds  of  drains.  It  depends  upon  the  same 
principle  as  that  described  for  setting  the  line,  and  con- 
sists of  setting  crossbars  at  the  stakes  instead  of  a  line 
and  then  testing  the  bottom  by  a  line  of  sight  over  a 
rod  of  the  same  length  as  that  at  which  the  bars  are 
set  above  the  grade  line.      Figure  25  will  make  the 


Fig.  25. — Grading  by  Sight  Line  and  Target. 

manner  of  using  them  plain.  The  targets,  as  they  are 
called,  are  bars  of  wood  about  3  feet  long,  and  are 
attached  to  an  iron  rod  by  means  of  adjustable  clamps, 
each  of  which  is  made  tight  by  a  thumb-nut.  The 
target  can  be  moved  up  or  down  upon  the  rod  or  set 
at  any  angle  desired.  The  iron  standard  can  be  thrust 
into  the  ground  where  it  will  remain  firm,  and  the  head 
levelled  and  brought  to  the  required  height,  at  which 
point  it  can  be  made  fast  by  the  thumb-nut.  When 
two  of  these  are  set,  the  grade  line  can  be  worked  to 
in  the  manner  shown  in  the  cut.  One  target  should 
be  painted  red,  the  other  white,  to  aid  in  drawing  a  line 
of  sight  over  them.  Whenever  there  is  a  change  of 
grade  the  target  should  be  reset,  and  at  such  times  a 
third  target  is  necessary. 

The  only  objection  to  this  method  is  that  some  work- 


Io6  ENGINEERING   FOR   LAND   DRAINAGE. 

men  do  not  have  *  *  a  good  eye  ' '  for  this  kind  of  work 
and  cannot  use  it. 

These  methods  of  grading  ditches  are  simple,  prac- 
tical, and  accurate,  and  in  the  hands  of  competent  work- 
men drains  can  be  constructed  with  as  great  accuracy 
as  our  city  sewers  are  laid  when  done  under  the  most 
rigid  supervision. 

Digging  the  Ditches  and  Laying  the  Tile. 

Not  every  laborer  can  dig  a  creditable  ditch  for  tile, 
but  perhaps  any  man  can  learn.  An  apprenticeship  of 
greater  or  less  duration  is  required  to  develop  a  skilful 
ditcher.  This  work  is  rapidly  passing  into  the  hands 
of  those  who  by  their  skill  merit  a  premium  in  wages 
readily  accorded  them  by  those  who  appreciate  thor- 
ough and  economical  work. 

The  work  of  constructing  a  tile  drain  should  begin 
at  the  outlet,  be  it  a  main  or  branch.  The  general 
method  that  should  be  followed  may  be  described,  but 
only  practice  will  give  that  swing  and  ease  of  motion 
with  which  the  trained  workmen  digs  the  ditch  and  laj^s 
the  tile.  The  ditch  should  be  started  straight  at  the 
top  and  the  curves  should  be  smooth,  not  uneven  and 
crooked.  Let  no  one  think  that  he  can  dig  such  a 
ditch  without  first  drawing  a  line  for  cutting  one  side 
of  it.  This  should  be  a  J-inch  rope  which  can  be  drawn 
tight  or  be  laid  to  form  a  suitable  curve.  The  top 
width  of  the  ditch  should  be  proportioned  to  the  depth 
to  which  it  must  be  made,  lo  or  12  inches  be- 
ing a  common  width  for  a  3 -foot  lateral  ditch.  A 
ditching  spade  with  blade  18  or  20  inches  long,  slightly 


GRADING    THE    DITCHES    FOR    TILE.  10/ 

curved  forward  and  straight  across  the  cutting-edge,  is 
used  for  this  work,  the  round-pointed  finishing  spade 
having  been  superseded  by  this.  The  workman  should 
thrust  the  blade  into  the  earth  a  little  quartering  to  the 
direction  of  the  line,  and  take  up  nearly  all  of  the  earth 
cut  loose  on  what  is  called  the  first  spading.  The  round- 
pointed  shovel  with  the  long  handle  should  now  be  used 
to  throw  out  the  loose  earth.  The  grading  line  having 
now  been  set  up  as  previously  described,  the  second 
or  finishing  spading  is  taken  out.  The  spade  should 
be  thrust  down  to  within  about  2  inches  of  the  bottom 
of  the  ditch,  and  when  about  4  feet  in  length  has  been 
excavated,  the  cleaning  scoop  should  be  used  to  remove 
the  loose  earth,  and  to  cut  a  curved  channel  just  large 
enough  to  receive  the  tile,  the  workmen  all  the  time 
standing  on  the  bench  above  the  bottom.  The  grade 
should  be  tested  in  the  way  heretofore  described,  and 
should  not  be  passed  until  the  few  feet  prepared  is  a 
perfect  section  of  the  continuous  line  as  laid  out.  If 
the  ditch  should  be  deeper  than  two  spadings,  as  of 
course  it  frequently  is,  enough  of  the  top  should  be 
taken  off  to  permit  the  grade  line  to  be  reached  by  two 
full  spadings.  In  case  of  larger  and  deeper  ditches  the 
top  width  must  be  increased  and  also  the  number  of 
spadings,  but  the  process  of  taking  the  last  one  and 
finishing  the  bottom  is  the  same. 

The  tile  from  6  inches  and  smaller  can  be  laid  with 
a  tile-hook  if  the  bottom  has  been  properly  prepared 
(Fig.  26).  They  may  be  turned  until  the  ends  fit  to- 
gether and  lie  firmly  in  the  channel,  which  has  been 
prepared  for  them  by  the  scoop.  When  finished,  this 
line    should    have  no    crooks   either    in    alignment  or 


io8 


ENGINEERING  FOR  LAND  DRAINAGE. 


grade.  The  curves  should  be  long,  so  that  by  turning 
the  tile  in  their  beds  close  joints  will  be  made.  If  an 
open  joint  is  necessary  on  the  outer  side  of  the  curve, 


Fig.  26. — Method  of  Using  Tile-hook. 


Tile-hook. 


a  bat  can  be  laid  over  it  and  clay  tamped  against  it  in 
such  a  way  that  it  will  be  secure.  All  cracks  that  are 
larger  than  i  inch  should  be  covered  with  bats.  Fol- 
lowing this  method  the  drain  is  finished  and  secured  as 
the  work  proceeds  from  the  outlet  up  grade.  When 
the  point  for  joining  a  branch  is  reached,  the  proper 
tile  with  Y  branch  should  be  placed  in  position  and 
the  opening  covered  securely  to  await  the  construc- 
tion of  the  branch  line. 

When  large  tiles  are  used — 9-inch  and  larger — it 
will  be  necessary  for  the  workman  to  walk  in  the  bot- 
tom as  he  grades,  which  work  must  be  done  with  the 
shovel.  The  same  care  should  be  used  in  securing  the 
proper  grade  as  above  noted.  Tile  should  be  laid  from 
the  outlet  up,  the  workman  standing  in  the  bottom  and 
placing,  them  with  his  hands.      They  should  be  secured 


GRADING   THE   DITCHES   FOR   TILE.  IO9 

in  place  by  clay  filling,  which  should  be  tamped  firmly 
between  the  sides  of  the  ditch  and  the  tile.  If  the  clay 
is  so  hard  that  it  must  be  loosened  by  the  pick,  the 
tediousness  and  expense  of  the  work  will  be  greatly  in- 
creased. 

It  will  be  observed  that  the  tools  necessary  for  this 
work  are  few:  the  line  or  target  for  obtaining  the 
grade  as  given  by  the  survey,  a  working  line  1 00  feet 
long,  ditching  spade,  round-pointed  shovel,  tile-hook, 
and  cleaning  scoop  of  the  size  required  for  the  tile  to 
be  laid.  The  practice  of  many  ditchers  is  to  lay  the 
tile  by  hand,  walking  backward  in  the  ditch  in  front  of 
the  tile  as  they  are  laid.  But  it  is  wholly  practicable, 
when  the  ditch  is  properly  prepared  at  the  bottom,  to 
lay  the  tile  with  a  hook  from  the  surface  in  a  perfectly, 
satisfactory  way  where  the  ditches  are  only  3  or  4  feet 
deep. 

Difficulties  in  Constructing  Tile  Drains, 

The  engineer  is  often  consulted  regarding  difficulties 
which  are  encountered  in  laying  tile,  and  in  his  work  as 
superintendent  he  is  charged  with  the  duty  of  helping 
out  \-he  contractor  when  he  meets  difficulties. 

Of  all  difficulties  which  are  encountered  in  construct- 
ing tile  drains,  quicksand  or  anything  that  resembles 
it  in  behavior  is  the  most  formidable  to  overcome.  The 
ingenuity  of  the  engineer  as  well  as  the  skill  of  the 
workman  is  often  taxed  to  the  utmost  in  such  cases. 
If  great  expense  is  to  be  avoided,  probably  the  most 
sensible  plan  is  first  to  select  a  dry  season  of  the  year 
in  which  to  dig  through  soil  known  to  contain  quick- 


no  ENGINEERING    FOR   LAND   DRAINAGE. 

sand.  Second,  lay  the  drain  as  far  into  the  treacherous 
soil  as  can  be  done  safely,  and  then  stop  the  work  for 
a  time  until  the  water  drains  out  to  some  extent  and 
then  proceed.  It  may  take  a  month  or  more  to  pass 
through  a  bad  place,  but  it  will  be  safer  and  cheaper 
than  to  attempt  to  force  through  by  the  use  of  sheeting 
or  boxing.  As  an  aid  to  the  solidifying  of  the  mass  so 
that  it  can  be  worked,  temporary  drains  may  be  laid 
as  far  as  possible  and  above  grade  in  order  to  more 
rapidly  draw  off  the  surplus  water. 

To  prevent  the  sand  from  entering  the  joints  of  the 
tile  either  tarred  paper  or  coarse  hay  or  grass  placed 
closely  about  the  joints  has  served  the  purpose,  care 
being  taken  in  all  cases  to  lay  the  tile  closely  together. 
It  is  highly  important  in  handling  quicksand  that  the 
workmen  should  not  disturb  the  material  more  than  is 
absolutely  necessary.  Each  shovelful  should  be  lifted 
carefully  and  without  moving  the  adjoining  sand. 
When  once  worked  up  into  a  thin  mortar  it  cannot  be 
handled  except  by  baling. 

Cleaning  Tile  Drains.  —  Notwithstanding  that  all 
possible  care  has  been  taken  to  prevent  mud  and  sand 
from  entering  tiles  during  the  construction  of  the  drain, 
it  frequently  occurs  that  they  will  be  found  more  or 
less  obstructed  from  this  cause.  If  the  tiles  are  in  the 
required  position,  and  are  all  right  with  the  exception 
of  the  obstruction,  do  not  disturb  them,  but  clean  out 
the  mud  or  sand  by  the  following  plan :  Remove  the 
earth  from  3  feet  of  the  drain  at  intervals  of  about  20 
feet.  Remove  these  3  feet  of  tile  and  take  out  all 
of  the  material  that  can  be  reached.  Tie  up  a  bundle 
of  straw  in  a  sack  of  such  size  that  it  will  nearly  fill 


>    GRADING   THE    DITCHES   FOR   TILE.  Ill 

the  bore  of  the  drain.  Attach  a  rope  securely  to  this 
and  pass  the  rope  through  the  drain  from  one  open- 
ing to  the  other.  This  can  be  done  by  means  of  a 
light  flexible  pole.  By  means  of  this  rope  pull  the 
swab  through  the  drain  and  as  the  material  is  forced  to 
the  opposite  end  let  it  be  dipped  or  shovelled  out.  It 
is  well  to  have  two  ropes  attached  to  the  swab  so  that 
having  passed  it  through  once  it  can  be  drawn  back 
and  the  operation  reversed.  All  this  should  be  done 
when  there  is  but  little  water  flowing  through  the  drain. 
After  the  stretch  of  drain  which  is  obstructed  is  cleaned 
out  return  the  tiles  which  were  removed  to  their  orig- 
inal position.  A  little  mud  or  sand  will  always  remain 
in  the  drain  after  it  has  been  scoured  in  this  way,  but 
it  will  be  readily  washed  out  when  the  drain  is  flushed, 
provided  the  drain  is  otherwise  in  perfect  condition. 

Submerged  Outlet. — Where  a  submerged  outlet  is 
necessary  the  drain  must  be  laid  when  the  ground  is 
dry  or  nearly  so.  A  submerged  outlet  in  itself  is  not 
objectionable,  but  it  should  be  understood  that  the  fall 
or  effective  head  of  the  drain  is  diminished  by  the  depth 
at  which  the  water  must  rise  above  the  outlet  before 
flowing  away,  and  the  line  of  soil  saturation  will  ex- 
tend back  on  a  level  until  it  intersects  the  line  of  the 
drain.  With  a  proper  head  no  injury  will  be  done  to 
the  drain  at  the  outlet,  and  the  rate  of  discharge  will 
be  nearly  as  great,  taking  into  account  the  diminished 
head,  as  though  the  discharge  were  into  the  open  air. 
Submerged  outlets  are  frequently  a  necessity  in  the 
drainage  of  level  tracts  into  artificial  outlets,  for  the 
reason  that  the  drains  must  be  placed  so  low  with  refer- 
ence  to   the   outlet  channel   that  the  tile   outlets  are 


112  ENGINEERING   FOR    LAND   DRAINAGE. 

flooded  at  every  considerable  rise  of  water  in  the  chan- 
nel into  which  they  discharge.  This  difficulty  should 
not  deter  one  from  laying  drains  under  such  conditions 
provided  the  water  in  the  open  channel  recedes  quickly. 
Where  the  drain  for  some  distance  back  has  a  pres- 
sure of  water  or  soil  upon  it,  its  action  is  similar  to 
that  of  an  iron  pipe,  the  head  of  drainage-water  from 
the  upper  levels  being  the  force  which  causes  the  sub- 
merged outlet  to  discharge.  The  objection  to  sub- 
merged outlets  is  less  for  open  soils  than  for  retentive 
ones,  since  in  open  soils  additional  head  is  given  to  the 
drain  when  the  soil  in  the  various  parts  of  the  tract  be- 
comes fully  saturated,  or  in  other  words  the  line  of 
saturation  rises  considerably  above  the  floor  of  the 
drains.  Where  the  soil  is  retentive,  the  weight  of  the 
soil  water  is  but  little  more  than  will  overcome  the  re- 
sistance which  the  soil  particles  ofler. 

Inspecting  Tile  Drains, 

The  most  definite  and  satisfactory  way  of  determin- 
ing whether  a  drain  has  been  laid  as  indicated  by  the 
survey  or  not  is  to  run  over  the  work  with  the  level. 
Determine  whether  the  tile  is  in  the  correct  position 
at  the  outlet  point  by  taking  a  rod-reading  on  its. grade 
stake  or  some  bench,  by  means  of  which  the  line  may 
be  reproduced.  Let  the  rodman  rod  up  on  top  of  the 
tile  at  each  station  and  also  between  each  station  and 
at  curves.  The  level  man  records  each  reading,  observ- 
ing whether  the  differences  correspond  with  the  grade 
as  laid  out,  allowing  in  all  cases  margin  enough  to 
cover  the  inequalities  of  the  tile  that  have  been  used. 


1 

GRADING   THE    DITCHES   FOR   TILE.  II3 

The  rodman  should  observe  the  joints  and  whether  im- 
proper tile  have  been  used.  If  the  line  '*  passes  "  the 
tile  are  ready  to  be  blinded  and  the  ditch  filled.  If  a 
line  has  been  constructed  skilfully  ^  inch  per  station 
should  cover  its  variation  from  a  true  grade.  The 
judgment  of  the  inspecting  engineer  should  be  some- 
what carefully  exercised  in  deciding  whether  certain 
faults  that  may  be  found  will  effect  the  efficiency  of 
the  work.  He  must,  however,  have  nerve  enough 
to  correct  faulty  construction  and  insist  upon  its  being 
made  right.  This  is  only  justice  to  the  employer  and 
works  no  hardship  upon  the  contractor,  if  what  was 
expected  of  him  was  fairly  set  forth  in  the  contract. 

Heavy  Rains  on  Unfinished  Drains. — During  the 
construction  of  a  drainage  system  the  work  is  often 
hindered  in  the  spring  of  the  year  by  heavy  rains  which 
fill  to  a  greater  or  less  extent  the  trenches  which  have 
been  dug  and  submerge  the  lines  of  tile  which  have 
been  laid.  In  the  case  of  mains  with  light  fall,  there 
is  considerable  risk  from  dirt  and  silt  which  may  be 
washed  into  the  drain  and  partially  obstruct  it.  The 
tile  drain  may  be  securely  closed  at  the  upper  end,  but 
if  the  water  is  permitted  to  flow  over  the  top  of  the 
tile,  the  drain  itself  being  nearly  empty,  the  weight  of 
the  water  passing  down  through  the  joints  until  the 
drain  is  full  carries  with  it  a  large  quantity  of  earth 
which  by  reason  of  the  lack  of  current  may  not  pass 
on  through  the  drain.  The  better  way  is  to  permJt  the 
water  to  enter  direct  through  the  end  of  the  drain  and 
fill  the  tile  completely,  letting  the  surplus  pass  on  over 
the  top  of  the  drain.  The  drain  being  full  and  the 
water  flowing  under  a  good  head  will  prevent  the  top 


114  ENGINEERING   FOR   LAND   DRAINAGE. 

water  from  carrying  silt  into  the  drains.  Small  drains, 
however,  should  be  securely  plugged  up  at  the  upper 
end.  Drains  which  in  some  way  have  become  par- 
tially obstructed  during  construction  may  be  cleaned  in 
this  way  provided  the  required  quantity  of  water  is  at 
hand  at  the  right  time.  It  is  desirable  to  fill  the 
trenches  as  soon  after  ,the  tile  are  laid  as  practicable  in 
order  to  lessen  the  risk  from  injury  by  freshets. 

Filling  the  Ditches, 

Enough  earth  should  be  thrown  upon  the  tile  after 
they  have  been  laid  and  inspected  to  secure  them  in 
their  position.  This  should  be  done  by  a  careful  work- 
man, who  should  see  that  the  earth  is  thrown  around 
and  over  the  tiles  in  such  a  way  that  they  will  not  be 
moved  by  any  subsequent  filling.  This  is  practically 
the  final  inspection  of  the  most  permanent  and  lasting 
improvement  which  can  be  made  in  a  soil.  Where  the 
drains  are  in  cultivated  land,  filling  may  be  completed 
with  a  plough  drawn  by  a  team  on  each  side  of  the  ditch. 
The  evener  used  on  this  plough  for  this  work  should  be 
about  1 6  feet  long.  It  is  assumed  that  the  excavated 
earth  has  been  thrown  in  about  equal  quantities  on  each 
side  of  the  ditch.  If  the  land  through  which  the  drains 
pass  is  in  grass,  a  V-shaped  scraper  made  for  the  pur- 
pose and  drawn  with  the  point  behind  should  be  used, 
as  this  will  move  the  earth  without  injuring  the  sod. 
Care  should  be  taken  to  place  all  of  the  excavated 
earth  in  and  directly  over  the  ditch.  If  this  is  not 
done,  there  will  be  a  depression  over  every  line  when 
the  loose  earth  settles  firmly  in  place.     The  fact  that 


GRADING    THE   DITCHES    FOR   TILE.  II 5 

the  loose  earth  continues  to.  settle  for  a  year  after  the 
ditches  have  been  filled  prevents  grass  from  taking 
quick  and  permanent  root.  For  this  reason  it  is  prefer- 
able to  cultivate  newly  drained  land  for  two  years  fol- 
lowing drainage.  The  filling  should  be  done  when  the 
waste  banks  are  not  wet,  in  which  case  the  earth  will 
not  roll  in  easily,  and  will  also  stick  to  the  tools. 
Where  it  is  necessary  to  fill  by  hand  work,  a  strong 
potato-hook  or  hoe  with  tines  instead  of  blade  will  be 
found  valuable.  With  it  the  earth  can  he  pulled  in 
more  rapidly  and  with  greater  ease  than  with  any  other 
tool,  especially  if  the  earth  is  in  a  sticky  condition. 

Markmg  Out  Tile  Ditches  with  the  Plough. 

The  method  of  opening  ditches  with  a  plough  is  prac- 
tised by  many  and  is  applicable  on  land  having  an  ex- 
cess of  fall,  so  that  careful  alignment  and  close  grading 
are  not  necessary  to  the  successful  operation  of  the 
completed  drains.  It  may  be  remarked  in  this  con- 
nection that  while  the  accurate  and  painstaking  work 
outlined  on  these  pages  is  always  necessary  in  drain- 
ing level  land,  it  is  not  so  important  on  land  which 
has  ample  natural  fall.  On  some  land  requiring  drain- 
age the  drains  can  scarcely  be  laid  in  such  a  way  as 
not  to  accomplish  the  end  sought,  especially  if  water  is 
present  when  they  are  laid.  Drains  laid  on  lines 
marked  out  and  partially  opened  by  the  plough  will 
lack  straightness  of  both  line  and  grade,  but  this  will 
not  destroy  their  efficiency  where  there  is  a  fall  of  6 
inches  to  30  inches  per  100  feet.  A  system  of  laterals 
with  heavy  grade   frequently  discharges  into  a  main 


tl6  ENGINEERING   FOR   LAND   DRAINAGE. 

with  light  grade,  in  which  case  good  judgment  must  be 
used  in  determining  the  size  of  the  receiving-main 
drain.  Ditching  contractors  who  dig  ditches  and  lay- 
tile  by  the  rod  usually  prefer  to  take  the  surface  with- 
out any  preliminary  work  of  the  plough. 

Outlet  Protection, 

Every  system  of  tile  drains  must  have  a  discharge 
through  some  main  into  a  natural  stream  or  open  ditch. 
The  banks  of  these  streams  or  ditches  are  continually 
subject  to  erosion,  so  that  it  is  often  difficult  to  maintain 
a  permanent  position  for  the  outlet  of  the  tile  drain. 
The  ends  should  be  protected  in  such  a  way  that  ani- 
mals cannot  enter  when  both  ditches  and  tile  are  nearly 
dry.  While  many  thousands  of  drains  are  not  pro- 
tected in  any  way,  instances  of  the  obstruction  of  drains 
by  animals  entering  and  not  being  able  to  get  out  oc- 
casionally occur,  so  that  it  is  wise  to  secure  the  dr-ain 
against  accidents  of  this  kind.  In  the  first  place  tile 
which  are  used  near  the  outlet  should  be  stoneware  or 
vitrified  pipe,  as  the  ordinary  red-clay  pipe  which  is 
serviceable  when  buried  will  decompose  and  crumble 
when  exposed  to  the  freezing  and  thawing  which  takes 
place  at  the  outlet  of  a  drain.  Better  than  this,  use 
good  sewer  pipe  with  sockets  for  1 5  feet  back  from  the 
outlet  and  cement  the  joints  with  cement  mortar.  The 
use  of  stone  for  an  abutment  for  the  outlet,  while  desir- 
able in  some  localities,  is  not  practicable  in  others.  The 
foundation  should  be  deep  and  it  should  be  set  well 
back  into  the  bank  so  that  the  water  of  the  stream 
will  not  wash  behind  it.      The  stone  should  be  laid  in 


GRADING    THE    DITCHES    FOR    TILE. 


17 


good  cement  mortar.      A  form  is  shown  in  Fig.   27. 
Probably  the  most  practicable  outlet  for  farm  drains, 


Fig.  27 — Section  of  Stone  Abutment  for  Drain  Outlet. 

especially  where  ditch  banks  are  subject  to  shifting,  is 
the  box  with  wire  bars  at  the  end,  as  shown  in  Fig.  28. 


Fig.  28.— Box  Outlets  for  Tile  Drains. 


The  Dox  should  be  not  less  than  12  feet  long  and  set 
on  the  grade  line  of  the  drain.  White-oak  planks  2 
inches  thick  should  be  used  if  they  can  be  had,  other- 
wise pine  or  hemlock.  Large  galvanized  iron  wires 
secured  in  a  vertical  position  about  2  inches  apart  across 
the  end  of  the  box  will  make    a    serviceable  screen. 


Il8  ENGINEERING   FOR   LAND    DRAINAGE. 

The  connection  of  the  box  with  the  end  of  the  line  of 
tile  should  be  thoroughly  and  carefully  made,  other- 
wise drainage-water  will  work  its  way  around  the  box 
and  underwash  it.  The  earth  should  be  most  thor- 
oughly tamped  about  the  box  as  the  filling  is  thrown 
in ;  in  no  case  should  it  be  loosely  filled,  as  is  done 
with  ordinary  ditches. 

The  Silt-basin, 

Silt-basins  are  often  injudiciously  used  in  a  drainage 
system.  They  serve  two  purposes:  one  to  collect 
the  water  of  several  drains  of  a  system  so  that  it  can  be 
combined  and  discharged  through  a  common  main,  and 
another  to  arrest  the  silt  which  a  drain  carries  and 
cause  it  to  deposit  itself  in  the  bottom  of  the  basin  or 
well  from  which  it  may  be  removed. 

The  effect  of  the  silt-basin  is  to  retard  the  flow  of  the 
water,  and  hence  should  never  be  used  where  this  will 
prove  injurious  to  the  drains.  The  breaking  of  the  cur- 
rent and  the  entrance  friction  of  the  outlet  pipe,  while 
it  causes  the  silt  to  be  deposited,  also  diminishes  the 
velocity  and  discharge  of  the  main  drain,  and  is  detri- 
mental to  the  action  of  the  drain  on  level  grades. 
Where  there  is  abundant  fall  and  the  entering  drains 
can  discharge  into  the  basin  not  less  than  one  foot 
above  the  top  of  the  outlet  drain  it  may  be  used. 

The  best  plan  for  collecting  the  water  of  several 
drains  into  one  is  by  means  of  the  Y  junction  and  a 
* '  drop  ' '  from  branch  into  main  as  noted  heretofore. 
The  current  is  preserved,  and  silt  is  carried  to  the  outlet 
before  it  is  deposited.     Where  the  drains  are  well  laid 


GRADING   THE    DITCHjSS   FOR   TILE.  1 19 

and  the  subsoil  is  clay,  there  is  no  occasion  for  the  use 
of  the  silt-basin  in  land  drainage  systems.  Its  use  for 
a  catch-basin  for  conveying  surface  water  into  tile 
drains  under  certain  conditions  will  be  described  here- 
after. 

Digging  Tile  Ditches  with  Machines, 

Many  machines  of  different  patterns  have  been  pat- 
ented, tried,  and  have  failed  to  displace  hand  labor  in 
diggifig  tile  ditches.  The  difficulties  to  overcome  do 
not  seem  insurmountable,  nevertheless  the  history  of 
such  machines  discloses  partial  successes  which  for  a 
time  promised  well,  but  in  the  end  did  not  meet  the  re- 
quirements of  the  work  in  all  kinds  and  conditions  of 
soils.  Ploughs  of  different  patterns  have  been  used  to 
aid  the  spade  by  loosening  the  earth  in  the  bottom  of 
the  ditch,  thereby  diminishing  the  labor  of  excavating 
somewhat.  The  machines  which  have  dug  the  ditch 
to  its  full  depth  at  one  passage  have  given  the  most 
satisfactory  results.  The  ditch  is  left  completed  to 
grade  and  ready  for  the  laying  of  the  tile,  the  exca- 
vated earth  is  left  loose  and  ready  to  be  easily  back- 
filled and  the  grade  is  more  easily  and  accurately  made 
than  by  a  machine  which  excavates  by  many  passages 
over  the  ground. 

One  of  these  machines  which  gives  excellent  results 
at  the  present  writing  and  has  been  more  successfully 
introduced  than  its  predecessors  is  distinctively  a 
traction  ditcher.  It  is  propelled  by  steam  power 
which  operates  a  cutting  wheel  and  at  the  same  time 
moves  the  machine  forward  by  traction,  excavating  a 


I20  ENGINEERING   FOR   LAND    DRAINAGE. 

completely  graded  ditch  at  the  rate  of  from  lO  to  20 
rods  per  hour.  It  is  governed  and  operated  in  the 
same  manner  as  a  traction  engine,  is  compactly  built 
and  easily  inanaged  by  two  men.  It  cannot  be  ex- 
pected that  a  machine  of  this  character  will  work  suc- 
cessfully in  ground  so  soft  that  it  will  not  bear  the 
weight  of  the  machine,  nor  in  land  full  of  stumps, 
stones,  and  large  roots. 

With  these  exceptions,  there  seem  to  be  no  diffi- 
culties which  are  not  successfully  met  by  this  machine. 

Contracts  for  Construction  of  Tile  Drains, 

The  construction  of  drains  for  improving  entire  farms 
and  large  areas  of  level  land  is  frequently  done  by  con- 
tract subject  to  competent  superintendence.  The  sys- 
tem is  laid  out  by  an  engineer  and  complete  plans  made 
for  the  work,  after  which  bids  for  the  construction  of 
the  drains  are  solicited.  The  furnishing  of  the  tile  and 
distribution  as  needed  upon  the  ground  is  usually  not 
included  in  the  ditching  contract,  neither  is  the  filling 
of  the  trenches. 

Tile  are  purchased  by  the  thousand  feet;  hauling 
from  the  railroad  station  or  factory  is  done  by  the  ton, 
the  weight  of  the  individual  pieces  of  different  sizes 
being  used  as  a  basis  for  determining  the  weight  of  the 
loads ;  the  digging  of  ditches  and  laying  of  tile  is  com- 
monly done  by  the  rod,  but  by  the  TOO  feet  would  be 
better,  and  filling  of  the  ditches  by  the  lOO  feet. 

The  following  general  specifications  and  contract 
have  been  found  useful  in  practice,  and  will  serve  as  a 
guide  in  preparing  specifications  for  other  work.     It 


GRADING   THE   DITCHES   FOR   TILE.  121 

will  be  observed  that  the  only  bond  or  security  required 
of  the  contractor  is  the  25  per  cent  retained  until  the 
completion  and  acceptance  of  the  work.  The  only 
method  of  securing  good  work  of  this  kind  is  to  give  it 
thorough  supervision  and  know  that  it  is  right  before 
the  drain  is  covered.  When  a  drain  has  been  accepted 
the  liability  of  the  contractor  should  cease  provided  the 
individual  Hne  has  been  finished.  The  retaining  of  25 
per  cent  is  made  for  the  purpose  of  securing  the  cor- 
rection of  any  faults  in  the  work  which  may  be  discov- 
ered before  the  drain  is  covered. 


GENERAL  SPECIFICATIONS   FOR  THE  CON- 
STRUCTION    OF   TILE    DRAINS. 

The  lines  for  the  ditches  are  indicated  on  the  field  by 
stakes  which  have  been  set  by  the  engineer,  and  the 
depths  and  grades  given  by  him  shall  constitute  a  part 
of  these  specifications. 

Digging  the  Ditches. — The  digging  of  each  ditch 
must  begin  at  its  outlet,  or  at  its  junction  with  another 
tile  drain,  arrd  proceed  toward  its  upper  end.  The 
ditch  must  be  dug  along  one  side  of  the  line  of  survey 
stakes,  and  about  ten  inches  distant  from  it,  in  a 
straight  and  neat  manner,  and  the  top  soil  thrown  on 
one  side  of  the  ditch  and  the  clay  on  the  other.  When 
a  change  in  the  direction  of  ditch  is  made,  it  must  be 
done  by  means  of  a  neat  curve,  but  in  all  cases  the  ditch 
must  be  kept  near  enough  to  the  stakes  so  that  they 
can  be  used  in  grading  the  bottom.  In  taking  out  the 
last  draft,  the  blade  of  the  spade  must  not  go  deeper  thr.n 


122  ENGINEERING  EOR    LAND    DRAINAGE. 

the  proposed  grade  line  or  bed  upon  which  the  tiles  are 
to  rest. 

Grading  the  Bottom. — The  ditch  must  be  dug  to  the 
depth  indicated  by  the  figures  given  with  the  survey, 
which  depth  is  to  be  measured  from  the  grade  stakes 
which  are  set  for  that  purpose,  and  graded  evenly  on 
the  bottom  by  means  of  the  ''  line  and  gauge  ' '  method, 
or  "target,"  or  any  other  equally  accurate  device  for 
obtaining  an  even  and  true  bottom  upon  which  to  lay 
the  tile.  The  bottom  must  be  dressed  with  the  tile 
hoe,  or  in  case  of  large  tiles,  with  the  shovel,  so  that 
a  groove  will  be  made  to  receive  the  tile,  and  when 
laid  in  it  they  will  remain  securely  in  place. 

Laying  the  Tile. — The  laying  of  the  tile  must  begin 
at  the  lower  end  and  proceed  up-stream.  The  tile 
must  be  laid  as  closely  as  practicable,  and  in  lines  free 
from  irregular  crooks,  the  pieces  being  turned  about 
until  the  upper  edge  closes,  unless  there  is  sand  or  fine 
silt  which  is  likely  to  run  into  the  tile,  in  which  case 
the  lower  edge  must  be  laid  close,  and  the  upper  side 
covered  with  clay  or  other  suitable  material.  When, 
in  making  turns,  or  by  reason  of  irregular-shaped  tile, 
a  crack  of  one  fourth  inch  or  more  is  necessarily  left, 
it  must  be  securely  covered  with  broken  pieces  of  tile. 
Junctions  with  branch  lines  must  be  carefully  and 
securely  made. 

Blinding  the  Tile. — After  the  tile  have  been  laid  and 
inspected  by  the  person  in  charge  of  the  work,  they 
must  be  covered  with  clay  to  a  depth  of  six  inches, 
unless,  in  the  judgment  of  the  superintendent,  the  tile 
are  sufficiently  firm,  so  that  complete  filling  of  the  ditch 
may  be  made  directly  upon  the  tile.     In  no  case  must 


GRADING   THE   DITCHES    FOR   TILE.  12 3 

the  tile  be  covered  with  sand  without  other  material 
being  first  used. 

Risk  During  Construction. — The  ditch  contractor 
must  assume  all  risks  from  storms  and  caving  in  of 
ditches,  and  when  each  drain  is  completed  it  must  be 
free  from  sand  and  mud  before  it  will  be  received  and 
paid  for  in  full.  In  case  it  is  found  impracticable,  by 
reason  of  bad  weather  or  unlooked-for  trouble  in  dig- 
ging the  ditch,  or  properly  laying  the  tile,  to  complete 
the  work  at  the  time  specified  in  the  contract,  the  time 
may  be  extended  as  may  be  mutually  agreed  upon  by 
employer  and  contractor.  The  contractor  shall  use  all 
necessary  precaution  to  .secure  his  work  from  injury 
while  he  is  constructing  the  drain. 

Tile  to  be  Used. — Tile  will  be  delivered  on  the 
ground  convenient  for  the  use  of  the  contractor.  No 
tile  must  be  laid  which  are  broken,  or  soft,  or  so  badly 
out  of  shape  that  they  cannot  be  well  laid  and  make  a 
good  and  satisfactory  drain. 

Payments  for  Work. — Unless  otherwise  hereafter 
agreed  upon,  the  contractor  may  at  any  time  claim  and 
receive  from  the  employer  seventy-five  per  cent  of  the 
value  of  completed  and  accepted  work  at  the  price 
agreed  upon  in  the  contract.  Twenty-five  per  cent 
will  be  retained  until  the  entire  work  contracted  for 
is  completed  and  accepted,  at  which  time  the  whole 
amount  due  will  be  paid. 

Prosecution  of  the  Work. — The  work  must  be  pushed 
as  fast  as  will  be  consistent  with  economy  and  good 
workmanship,  and  must  not  be  left  by  the  contractor 
for  the  purpose  of  working  upon  other  contracts,  ex- 
cept by  permission  and  consent  of  the  employer.      All 


124  ENGINEERING   FOR    LAND   DRAINAGE. 

survey  stakes  shall  be  preserved  and  every  means 
taken  to  do  the  work  in  a  first-class  manner. 

Failure  to  Comply  With  Specifications. — In  case 
the  contractor  shall  fail  to  comply  with  the  specifica- 
tions, or  refuse  to  correct  faults  in  the  work  as  soon  as 
they  are  pointed  out  by  the  person  in  charge,  the  em- 
ployer may  declare  the  contract  void,  and  the  con- 
tractor, upon  receiving  seventy-five  per  cent  of  the 
value  of  completed  drains  at  the  price  agreed  upon, 
shall  release  the  work  and  the  employer  may  let  it  to 
other  parties. 

Sub-letting  Work. — The  contractor  shall  not  sub- 
let any  part  of  the  work  in  such  a  way  that  he  does  not 
remain  personally  responsible^  nor  will  any  other  party 
be  recognized  in  the  payment  for  work. 

Plans  and  Tools. — The  contractor  shall  furnish  all 
tools  which  are  necessary  to  be  used  in  digging  the 
ditches,  grading  the  bottom,  and  laying  the  tile.  In 
case  it  is  necessary  to  use  curbing  for  the  ditches,  or 
outside  material  for  covering  the  tile  where  sand  or 
slush  is  encountered,  the  employer  shall  furnish  the 
same  upon  the  ground  convenient  for  use. 

All  plans  and  figures  furnished  by  the  engineer,  to- 
gether with  the  drawings  and  explanations,  shall  be 
considered  a  part  of  these  specifications. 


GRADING   THE   DITCHES    FOR   TILE.  12$ 

CONTRACT. 

It  is  hereby  agreed  between 

employer,  and  ... ,  contractor, 

that  the  said will  construct  the  fol- 
lowing named  or  described  tile  drains  in  accordance  with  the  foregoing 
specifications,  at  the  prices  herein  named,  and  that  he  will  begin  the 
work  on  or  before and  complete  the  same  by 


Witness  the  hands  of  the  respective  parties,  this day  of 

,  Employer. 

,  Contractor. 


CHAPTER    IX. 
FLOW  OF  WATER  THROUGH  PIPES. 

Before  taking  up  the  subject  of  the  size  of  drains  it 
is  proposed  to  outline  briefly  that  branch  of  hydraulics 
which  relates  to  the  flow  of  water  through  pipes,  in 
order  that  the  beginning  engineer  may  have  the  basis 
upon  which  to  study  the  flow  of  water  through  tile 
drains.  While  there  have  been  very  elaborate  investi- 
gations made  upon  this  subject,  it  is  only  necessary  in 
this  connection  to  outline  the  facts  without  entering 
into  a  full  analytical  discussion  of  the  matter. 

It  should  be  borne  in  mind  by  those  who  are  plan- 
ning drainage  works  that  gravity  is  the  sole  cause  of 
flow  in  water.  The  flow  of  water  in  a  drain  of  whatever 
kind  is  owing  to  the  inclination  of  the  surface  of  the 
fluid.  The  same  universal  force  causes  unsupported 
bodies  to  fall  vertically,  a  ball  to  roll  down  an  incline, 
and  water  to  flow  along  a  channel  or  through  a  pipe. 
The  formula  used  to  express  the  theoretical  velocity  due 
to  gravity  is 

V  =  V2ghy 
where  v  =  velocity  in  feet  per  second; 
g  =  accelerating  force  of  gravity; 
h  =  spac^  through  which  the  body  falls. 

It  has  been  found  by  experiment  that  a  body  in 
vacuum  at  the  level  of  the  sea  passes  through  a  space  of 

126 


FLOW   OF   WATER    THROUGH   PIPES. 


127 


16. 1  feet  during  the  first  second,  and  at  the  end  of 
that  time  has  acquired  a  velocity  of  32.2  feet.  The 
velocity  at  the  end  of  each  succeeding  second  of  time  is 

32.2  feet  greater  than  it  was  at  the  end  of  the  preced- 
ing second.  This  is  called  the  accelerating  force  of 
gravity  and  is  usually  designated  by  g.  Knowing 
the  height  that  the  body  has  fallen  at  any  time,  the 
velocity  may  be  determined.  The  following  table 
shows  at  once  the  relation  of  time,  space,  velocity,  and 
accelerating  force  of  the  action  of  gravity  upon  falling 
bodies  during  the  first  five  seconds : 


FALLING  BODIES  DURING  FIRST  FIVE  SECONDS 

• 

Time .  .  . 

I  sec. 

2  sec. 

3  sec. 

4  sec. 

5  sec. 

Space  =  fc 

16. 1 
32.2 
32.2 

64.4 
64.4 
32.2 

144.9 
96.6 
32.2 

257.6 

128.8 

32.2 

402.  s 

161. 0 

Accel,  force  =  g 

32.2 

Water  flowing  down  an  inclined  surface  would  follow 
the  same  law  were  it  not  for  resistances  of  various 
kinds  which  constantly  act  upon  the  particles  of  water 
as  they  descend  and  produce  a  uniform  flow  where  the 
resistance  is  constant.  Were  this  not  the  case,  our 
ponds  and  lakes  would  soon  become  dry,  and  our 
brooks  and  rivers  would  for  a  time  become  dangerous 
torrents.  The  equilibrium  of  natural  forces  would  at 
once  become  unbalanced. 

It  has  been  the  life-long  work  of  many  eminent  hy- 
draulicians  to  determine  by  practical  experiments  the 
value  of  these  retarding  forces  and  by  introducing  them 
into  the  gravity  formula  to  so  modify  it  that  it  shall 
be  a  correct  expression  for  the  flow  of  water  under  given 
conditions  and  thus  become  of  use  in  practical  affairs. 


128  ENGINEERING   FOR    LAND   DRAINAGE. 

Simple  as  this  task  may  at  first  seem,  it  has  occupied 
the  time  and  attention  of  many  experimenters  who  are 
justly  noted  by  reason  of  their  researches  in  this  de- 
partment of  practical  science. 

When  the  flow  of  water  through  pipes  is  considered, 
the  resistances  to  gravity  are,  first,  resistance  to  en- 
trance of  water  into  the  pipe;  second,  the  resistance 
offered  by  the  walls  of  the  pipe  with  which  the  water 
comes  in  contact.  The  first  will  vary  with  the  kind  of 
opening  through  which  the  water  enters  the  pipe,  the 
second  with  the  kind  of  pipe  and  its  length  and  the 
head  which  produces  flow. 

Many  of  the  formulas  deduced  agree  with  each  other 
in  the  results  obtained  from  them  sufficiently  near  for 
practical  purposes,  yet  there  is  a  wide  difference  in  their 
simplicity  and  availability  for  use.  There  is  one  which 
represents  at  a  glance  the  corrections  that  must  be  ap- 
plied to  the  gravity  formula,  so  that  it  will  express  the 
velocity  of  water  in  pipes.  It  is  known  as  Weisbach's 
formula  and  is  expressed  as  follows : 

^  =  —r -^»    ....    (2) 

where  e  =  coefficient  of  resistance  to  entrance  of  water 
into  pipe ; 

c  =  coefficient  of  friction  of  pipe; 

/  =  length  of  pipe  in  feet ; 

d  =  diameter  of  pipe  in  feet. 

The  numerator  of  the  second  number  of  this  equation 
is  the  theoretical  velocity  of  falling  bodies.     The  de- 


FLOW   OF   WATER   THROUGH   PIPES.  I29 

nominator  represents  the  resistance  offered  by  the  pipe 
to  the  flow  of  water  through  it  as  determined  by  the 
author  of  this  formula.  When  the  numerical  values 
found  for  e  and  c  are  substituted,  the  result  is  the  veloc- 
ity formula  for  falling  bodies  modified  so  that  it  will 
apply  to  the  velocity  of  water  in  pipes. 

There  are  formulas  which  are  just  as  accurate  and 
possess  the  very  desirable  excellence  of  greater  sim- 
plicity in  which  g  and  h  are  combined  with  quantities 
whose  value  has  been  determined  by  experiment. 
Beardmore's  formula  is  one  of  these  simple  expressions: 

V  =  100  VRS,    .....     (3) 

where  R  =  hydraulic  mean  depth 

area  of  waterway       a 

wet  perimeter     ~  /  * 

-         .         .   ,  head  in  feet         k 

6  =  sme  of  slope  =  . -. — ^r—. —  =  t  . 

length  01  pipe       / 

This  formula  written  out  in  full  is  as  follows: 


V  =   IOGa  / 

V  : 


area  head  ^  ^ 

X  Tz;::;^;^^:^^-  ■    (4) 


perimeter       length  of  pipe* 

In  this  expression  the  constants  g  and  coefficients 
of  friction  are  merged  into  one  common  constant,  100, 
and  the  variable  quantities  are  expressed  in  terms  which 
may  always  be  determined  for  each  particular  pipe. 

The  above  are  examples  of  reliable  velocity  formulas 
made  use  of  by  engineers  in  computing  the  flow  of  water 
through  pipes  of  various  kinds  and  sewers  of  various 
descriptions  when  the  head  of  water  is  known  and  the 
pipes  come  within  reasonable  limits  of  perfection  in 
workmanship.     The  American  unit  is  feet  per  second 


I30  ENGINEERING    FOR    LAND   DRAINAGE. 

and  the  quantity  discharged  is  cubic  feet  per  second. 
When  the  velocity  is  found  the  discharge  is  obtained 
by  multiplying  the  area  of  the  column  or  jet  of  water 
expressed  in  square  feet  by  the  velocity  in  feet  per  sec- 
ond. The  result  will  be  cubic  feet  per  second.  By 
formula  the  expression  would  be 

Q-=^av, (S) 

where  Q  =  quantity  in  cubic  feet ; 

-     a   =  area  of  column  of  flowing  water; 
V  =  velocity  as  determined  by  formula. 

Substituting  the  value  of  v  in  equation  5  we  have 

Q  =  100a  VRS       .     .     .     •     (6) 

Flow  of  Water  through  Tile  Drains, 

As  previously  stated,  the  object  of  draining  land  is 
the  removal  of  such  soil  water  as  is  not  needed  for  the 
profitable  growth  of  the  plants  we  desire  to  produce. 
The  source  of  all  water  is  the  rainfall  as  it  is  distributed 
over  the  surface  of  the  soil  at  irregular  times  and  in 
varying  quantities.  The  removal  of  the  part  not 
wanted  is  accomplished  by  underground  tile  drains, 
the  water  reaching  them  by  percolation  through  the 
soil.  The  problem  in  drainage  hydraulics  is  not  only 
to  determine  the  quantity  of  the  water  which  a  certain 
drain  will  carry,  but  also  to  ascertain  how  much  water 
should  be  removed  from  the  soil  at  certain  times  in 
order  to  place  the  land  in  the  desired  condition. 

The  very  quick  and  rapid  removal  of  soil  water  is 
not  desirable  in  the  drainage  of  farm  land.     The  object 


A 


FLOW   OF   WATER   THROUGH   PIPES.  131 

should  be  to  remove  the  surface  water  quite  quickly  and 
secure  a  gradual  movement  of  sub-surface  water  through 
the  soil  into  the  drains.  The  action  of  the  water  in 
passing  slowly  through  the  soil  is  beneficial  in  imparting 
to  it  such  fertilizing  gases  as  it  may  have  absorbed  from 
the  atmosphere,  and  in  disintegrating  soil  particles  and 
helping  to  prepare  them  for  plant  food.  With  this  ob- 
ject in  view,  sufficient  drainage  is  better  than  too  much. 

The  rainfall  is  exceedingly  variable  both  with  respect 
to  the  season  of  precipitation  and  the  quantity  which 
falls,  so  that  a  system  of  drains  which  would  prove 
ample  during  one  year,  or  even  for  a  series  of  years, 
would  at  other  times  become  overcharged  and  prove 
insufficient  for  the  work  desired. 

The  land  to  be  drained  is  in  some  localities  a  level 
tract,  in  others  it  is  broken  up  by  ridges,  slopes,  ponds, 
and  swamps  alternating  in  irregular  variety,  thereby 
greatly  complicating  the  plans  which  must  be  used  for 
draining  successfully  as  well  as  the  determination  of  the 
size  of  the  drains  for  the  same. 

The  drains  ordinarily  used  for  the  work  are  not  uni- 
form either  in  the  quality  of  the  material  or  excellence 
of  the  workmanship  when  constructed.  The  drain  re- 
ceives water  at  all  of  the  joints,  and  in  the  case  of  mains 
at  various  points  where  branches  join.  These  discharge 
into  the  main  under  varying  heads  and  grades. 

It  follows  that  it  is  no  easy  matter  to  formulate  the 
elements  which  enter  into  economical  and  efficient  land 
drainage  so  as  to  put  the  subject  of  the  flow  of  water  in 
drains  on  a  scientific  and  at  the  same  time  a  practical 
basis. 

It  has  been  found,  however,   by  observations  and 


132  ENGINEERING  FOR  LAND  DRAINAGE. 

experimental  tests  that  the  existing  formulas  for  the 
flow  of  water  through  pipes  are  with  some  allowances 
more  applicable  to  tile  drains  than  at  first  would  be 
thought  possible.  The  art  of  using  a  formula  success- 
fully is  in  bringing  to  it  in  proper  form  the  data  which 
should  be  used  and  in  making  the  proper  assumptions 
which  should  precede  the  application  of  any  formula. 

The  following  formula  has  been  found  to  be  simple 
and  of  easy  application  and  has  been  verified  by  use  of 
a  current  meter  upon  the  discharge  from  lines  of  tile  in 
which  the  grade  of  the  drain  and  the  quality  of  work- 
manship in  its  construction  were  known : 


For  velocity      v  =  4^\/  ^  _.     ^       .     (7)* 

For  discharge  Q  =  A^asJ  j-^^^      .     (8) 

where  v  =  velocity  in  feet  per  second ; 
^=  diameter  of  tile  in  feet; 
/=  total  fall  in  length  of  drain  in  feet; 
/  =  length  of  drain  in  feet ; 
a  =  area,  of  tile  in  feet ; 
Q  =  discharge  in  cubic  feet  per  second. 

All  measurements  to  be  taken  in  feet. 

Application  of  the  Formula. 

This  formula  will  give  quite  correctly  the  velocity 
and  discharge  from  lines  of  tile  drains  which  are  laid  in 
a  first-class  manner,  within  certain  limitations  as  to  size 
and  length,  which  will  hereafter  be  considered.     In  ap- 

*  Known  as  Poncelet's  formula. 


FLOW   OF    WATER   THROUGH   PIPES.  1 33 

plying  it  for  determining  the  size  of  main  drains  the 
question  arises  how  much  water  per  acre  should  be 
taken  off  the  land  in  a  given  time  Many  engineers 
who  discuss  this  branch  of  the  drainage  subject  pro- 
pose some  formula  which  is  used  for  water  supply  or  for 
city  sewerage  and  by  it  compute  the  size  a  drain  should 
be  to  carry  off  i  inch  or  J  inch  of  water  in  twenty- 
four  hours  These  results  differ  so  widely  from  the 
most  approved  practice  in  drainage  that  they  are  in  dis- 
repute among  practical  men  and  are  not  sustained  by 
the  test  of  experience.  The  discrepancy  is  explained 
by  saying  that  drainage  is  not  thorough  as  practised. 
Be  that  as  it  may,  observation  and  experiment  demon- 
strate quite  conclusively  that  where  thorough  work  is 
practised,  tile  drains  do  not  remove  ^  inch  of  water 
from  the  soil  in  twenty-four  hours.  While  this  standard 
is  about  correct  for  open  ditches,  it  does  not  apply  to 
ordinary  tile  drainage,  except  under  special  conditions. 

The  results  of  experiments  and  observations  in  re- 
cent years  seem  to  sustain  the  practice  of  many  careful 
engineers  who  state  that  the  removal  of  J  inch  depth 
of  water  in  twenty-fours  hours  by  tile  drains  meets  the 
requirements  of  the  average  soil,  and  may  be  regarded 
as  a  basis  upon  which  to  make  computations  for  the  size 
of  mains,  subject  to  such  changes  as  the  special  tract  to 
be  drained  may  demand.  The  following  are  some  of 
the  considerations  which  have  a  bearing  upon  this 
question. 

A  drained  soil  is  a  reservoir.  The  ideal  drained 
field  is  one  in  which  water  sinks  downward  through  the 
soil  from  the  point  where  it  falls,  the  surplus  passing 
into  some  drain  near  by  and  thence  into  the  main.     If 


134  ENGINEERING    FOR   LAND    DRAINAGE. 

the  drains  are  laid  3  feet  deep  we  have  a  soil  res- 
ervoir of  that  depth  which,  if  it  is  very  dry,  will  hold 
one  third  of  its  depth  in  water.  But  this  condition  is 
rarely  if  ever  met  with  in  practice,  but  if  the  soil  is 
well  drained  it  will  take  2  inches  of  rain  to  saturate  it, 
the  amount,  however,  depending  upon  the  soil.  The 
evaporation,  which  in  the  summer  begins  at  once,  and 
also  the  absorption  and  evaporation  of  moisture  by 
plants,  make  a  large  draft  upon  water  of  the  soil. 

Most  of  the  data  on  evaporation  and  drainage  are 
taken  from  observations  made  in  England.  This  does 
not  apply  to  our  soil  and  climate  for  the  reason  that 
the  atmosphere  of  England  is  much  more  humid  and 
the  evaporation  from  plants  and  soil  much  less  than  it 
is  in  this  country.  It  has  been  shown  by  good  authority 
that  evaporation  from  soil  and  water  in  this  country 
is  fully  twice  as  great  as  that  in  England,  and  it  fol- 
lows that  a  like  difference  should  exist  in  evaporation 
from  plants. 

An  experiment  made  in  1889  at  Uniontown,  Ala., 
for  the  purpose  of  finding  the  percentage  of  the  rainfall 
which  passes  off  through  tile  drains  is  stated  briefly  as 
follows : 

The  tract  of  land  consisted  of  three  acres  drained  by 
lines  of  tile  3  feet  deep  and  30  feet  apart.  The  meas- 
urements recorded  were  the  outflow  of  excessive  rainfall 
April  1 3th  and  14th,  when  3. 39  inches  fell  in  twenty-four 
hours  upon  land  denuded  of  vegetation  by  the  prepara- 
tion for  spring  crops.  From  the  measurements  made  it 
appears  that  the  greatest  discharge  from  the  drains  was 
about  eighteen  hours  after  the  first  heavy  rainfall,  at 
which  time  the  drains  were  discharging  J  of  an  inch 


FLOW   OF   WATER   THROUGH   PIPES.  I35 

in  twenty-four  hours.     At  the  end  of  nine  days  only  23 
per  cent  of  the  rainfall  had  passed  off  in  drainage. 

It  must  be  admitted  .that  there  is  a  wide  range  of 
differences  in  the  recorded  results  of  experiments  made 
for  the  purpose  of  determining  the  percentage  of  drain- 
age to  rainfall.  One  series  of  carefully  constructed 
observations  gives  the  average  filtration  for  a  series  of 
years  at  5  per  cent  of  the  rainfall.  Another  series  ap- 
parently as  reliable  gives  42  per  cent.  All  of  them, 
however,  give  a  small  percentage  for  the  months  of 
May,  June,  July,  and  August.  The  above  observa- 
tions were  not  made  in  this  country,  and  furthermore 
the  means  which  were  used  in  arriving  at  these  conclu- 
sions were  crude. 

Soil  water  should  occupy  from  10  to  30  per  cent  of  the 
empty  space  in  productive  soils.  Not  until  the  quan- 
tity exceeds  this  will  the  drains  be  called  into  action. 
Again  the  subsoil  for  a  foot  or  more  above  the  plane 
of  the  lateral  drains  may  be  saturated  for  a  time  and 
no  injury  result  to  the  upper  soil  or  the  growth  upon  it. 
One  benefit  resulting  from  a  system  of  underdrains 
which  is  often  overlooked  is  that  soil  water  even  when 
excessive  does  not  stagnate.  It  moves  constantly  in 
the  direction  of  the  drains,  and  air  fills  the  space  for- 
merly occupied  by  surplus  water. 

There  is  another  fact  bearing  on  this  question  which 
should  be  considered  in  this  connection.  Owing  to 
the  rapidity  of  rainfall  on  some  occasions,  and  the 
inability  of  some  soils  to  absorb  the  water  quickly 
enough,  a  certain  portion  of  it  flows  over  the  surface 
and  collects  in  depressions  near  by  and  must  be  re- 
moved from  those  points  either  through  the  underdrains 


136  ENGINEERING  FOR   LAND   DRAINAGE. 

or  by  some  surface  relief.  Such  conditions  give  rise  to 
the  complaint  that  the  drains  are  not  sufficiently  large. 
Additional  drainage  should  be  provided  at  such  depres- 
sions either  by  the  use  of  more  than  the  usual  number 
of  underdrains  or  by  some  surface  overflow.  It  is 
always  wise  to  place  the  drains  closer  together  in  the 
depressions  than  on  the  surrounding  land,  not  that 
more  water  is  precipitated  there,  but  they  are  the  nat- 
ural receptacles  for  surface  overflow.  Every  means 
possible  should  be  taken  to  intercept  overflow  water 
from  the  higher  lands.  The  actual  head  under  which  a 
drain  works  when  discharging  its  maximum  quantity  is 
the  difference  in  elevation  of  its  outlet  and  head  end,  to 
which  should  be  added  at  least  one  half  of  the  depth  of 
the  drain  at  the  upper  end.  A  porous  soil  filled  with 
water  nearly  to  the  surface  easily  gives  this  additional 
head  and  should  be  used  in  the  formula  when  comput- 
ing the  full  capacity  of  the  drain.  It  is  the  impression 
among  many  engineers  that  a  city  pipe  sewer  forms  a 
more  perfect  channel  for  the  flow  of  water  than  a  tile 
drain.  Observations  upon  this  point  indicate  that  this 
opinion  is  unfounded.  A  well-laid  tile  drain  is  graded 
as  accurately  as  the  best  of  sewers ;  there  is  less  resist- 
ance at  the  joints,  for  the  cemented  joints  in  a  pipe 
sewer  are  rarely  smooth  and  perfect;  the  flow  of  a 
sewer  must  carry  more  or  less  solid  matter,  and  the 
surface  of  the  pipe  is  often  coated  with  a  slime  which 
retards  flow,  while  on  the  other  hand  the  water  in  a  tile 
drain  is  clear  and  the  walls  of  the  tile  are  clean. 

Keeping  in  mind  the  cautions  and  conditions  here- 
tofore enjoined,  formula  7  may  be  applied  for  determin- 
ing the  size  of  mains  and  submains.      Assume  a  size 


FLOW   OF   WATER   THROUGH   PIPES. 


137 


Table  2. 
areas  of  tile  in  square  feet. 


Dia.  n 

Dia.  in 

Area  in  . 

Dia.  in 

Dia.  in 

Area  in 

Inches. 

Feet. 

Sq.  Ft. 

Inches 

Feet/. 

Sq  Ft 

2 

.1667 

.0218 

II 

.9167 

.6600 

3 

.2500 

.0401 

12 

1. 000 

•  7854 

3* 

,2917 

.0668 

13 

1.083 

.9218 

4 

.3333 

.0873 

14 

1. 167 

1 .069 

5 

.4167 

.1363 

IS 

1.250 

1.227 

6 

.5000 

.1964 

16 

1.333 

1.396 

7 

.5833 

.2673 

17 

1.417 

1.S76 

8 

.6667 

.3491 

18 

1.500 

1.767 

9 

.7500 

.44t8 

19 

1.583 

1.969 

10 

.8333 

•5454 

20 

1.667 

2.i8a 

Table  3. 

HEAD  IN  INCHES  PER  100  FT. 

REDUCED  TO  FEET  PER  100 

FT  AND  FEET  PER  MILE. 


Table  4. 

contents  of  tile  in  one 
foot  of  length. 


Head 

in 

Head  in 

Head  in 

Ins.  per 
loo  Ft. 

Ft.  per 

Ft.  per 

loo  Ft. 

Mile. 

^ 

.0052 

.274 

.0104 

•  549 

.0208 

1.098 

.0313 

1.652 

.0417 

2.201 

.0521 

2.750 

.0625 

3.300 

.0729 

3.849 

I 

.0833 

4.398 

^ 

.0938 

4952 

■ 

.1042 

S-501 

1 

.1146 

6.050 

i 

.1250 

6.600 

.1354 

7.149 

■ 

.1458 

7.698 

.1563 

8.252 

a 

.1667 

8.801 

.1771 

9.3-';o 

.1875 

9.900 

.1979 

10.449 

.  2083 

10.998 

.2188 

11.552 

,  2292 

12. 101 

1 

.2396 

12.650 

3 

.2500 

13.200 

.2604 

13-749 

.2708 

14.298 

.2813 

14.852 

.2917 

15.401 

.3020 

15.950 

* 

.3125 

16.500 

1 

.3229 

1 7 . 049 

4 

.3333 

17.598 

Dia  in 
Inches. 

Cu.  Ft. 
in  I  Ft. 
Length. 

Gallons  of 

231  Cu  Ins. 

in  I  Ft. 

Length 

2 

.0218 

.  1632 

2i 

.0341 

.2550 

3 

.0491 

.3672 

3i 

.0668 

.4998 

4 

.0873 

.6528 

4* 

.1104 

.8263 

5 

.1364 

1 .020 

Si 

.1650 

1-234 

6 

.1964 

1.469 

7 

.2673 

1.999 

8 

.3491 

2. 611 

9 

.4418 

3305 

10 

.5454 

4.080 

11 

.6600 

4937 

12 

.7854 

5.875 

13 

.  92 1 8 

6.895 

14 

1.069 

7.997 

IS 

1.227 

9.180 

16 

1.396 

10.44 

17 

1.576 

11.79 

18 

1.767 

13.22 

19 

1.969 

14  73 

30 

3.182 

16.33 

138 


ENGINEERING  FOR  LAND  DRAINAGE. 


and  apply  the  formula,  being  careful  to  consider  the 
physical  conditions  of  the  area  for  which  the  computa- 
tion is  made.  Substitute  the  proper  numbers  in  formula 
7  and  find  the  value  of  v ;  multiply  the  value  of  v  by 
the  area  of  the  tile  as  found  in  Table  2  to  find  value  of 
Q.  The  result  will  be  the  quantity  of  water  in  cubic 
feet  per  second  which  the  tile  will  discharge.  Divide 
this  number  by  the  number  in  Table  5,  which  expresses 
the  quantity  of  rainfall  per  acre  which  it  is  desired  to 
remove  per  second  in  twenty-four  hours.  The  result 
will  be  the  number  of  acres  which  the  given  drain  will 
afford  an  outlet  for. 

Table  5. 

table  of  cubic  feet  per  second  which  must  be  dis- 
charged from  a  drain  to  relieve  one  acre  of  land 
op  various  depths  of  water  in  24  hours. 

.0420  cu.  ft I  inch  per  acre 

.0315   **  ** f    " 

.0210  '*  ** J    *' 

.0140  *•  ** \    *' 

.0105   **  ** i    " 

.0052   *'  ** •. i    •* 

Example, — How  many  acres  will  a  6- inch  tile  drain,  1000  feet  long, 
laid  on  a  grade  of  3  inches  per  100  feet  and  3  feet  deep  at  the  upper 
end,  computing  on  the  J -inch  standard  ? 


Formula  (7):       v 


=  ''  \/l 


df 


+  540^ 


/=  2.5  +  1.5=4; 
/  -f  54^  =  1027. 


[027 


=  .00194 


48|/T 


00194 


=  2.112 


^  =  flz/  =  2. 112  X  .1964  =  -41479. 


Acres  = 


•41479 
.0105 


=  39-5- 


FLOW   OF   WATER   THROUGH   PIPES.  1 39 

Note.— Add  one  half  the  depth  of  drain  at  upper  end  =1.5  feet  to 
the  fall  for  vahie  of  /. 

How  many  acres  when  the  tile  is  laid  on  a  grade  of  .  10  foot  per  100 
feet? 
.5  X  2.5  =  1.25  ^df.  d^  .5; 

/=  I  4-1.5  =  2.5; 
/  -f-  54^  =  1027. 

JLIL  _  .00121;     |/.OOI2I=:  .0348  !    48  i/!oOI2I=   1.67  =  z/. 
1027  ' 

Q  =  i.ey  X  .1964  =■-  .32798. 
.327988 

*  Acres  =    ^     - —  =  ^1.2^. 

.0105  ^      ^ 

Note. — Making/  =  grade  only,  which  should  be  used  where  the 
soil  is  close.     Acres  =  20. 

To  find  the  volume  of  water  in  cubic  feet  per  second 
which  a  tile  drain  will  discharge,  multiply  the  computed 
velocity  in  feet  per  second  for  the  diameter  of  tile  re- 
quired by  the  number  given  in  column  3  of  Table  2. 

Note. — To  reduce  cubic  feet  to  gallons  multiply  by  7.48. 

Weight  of  I  cubic  foot  of  water 62^  lbs. 

Weight  of  I  gallon  of  water 8.35  lbs. 

Seconds  in  i  hour . . . .' 3600 

Seconds  in  24  hours 86,400 

Number  of  cubic  feet  of  water  on  i  acre  of  land  when  covered  i 
inch  deep 3630 

The  Total  Head  or  Fall  that  should  be  Used In 

considering  the  total  fall  of  a  main  drain  it  is  quite  evi- 
dent that  the  head  which  generates  the  flow  is  not  in  all 
cases  the  difference  in  elevation  of  the  two  ends  of  the 
line,  but  when  supplied  by  a  system  of  laterals  which 
have  a  greater  rate  of  incline  the  velocity  head  will  be 
increased  by  the  laterals.  Also,  if  the  soil  is  saturated 
above  the  tile  to  nearly  the  surface,  and  the  soil  is  free 
and  open,  the  rnain  drain  as  well  as  the  laterals  will 


I40  ENGINEERING   FOR    LAND   DRAINAGE. 

receive  added  head  from  this  source.  While  these 
forces  are  variable  and  difficult  to  formulate,  it  is  safe 
to  assume  a  small  additional  head  made  up  from  these 
sources. 

To  find  the  total  flood  head,  find  how  much  higher 
the  upper  terminal  of  each  lateral  or  sub-main  is  than 
the  upper  terminal  of  the  main  drain,  take  the  mean  of 
the  differences  and  add  it  to  the  head  of  the  main.  To 
this  result  add  one  half  of  the  depth  of  the  upper  end 
of  the  main,  for  open  soils  only,  for  the  value  of/"  in 
the  formula. 

By  Formula. 

f=A+^+iC (9) 

h  =  head  of  main. 

d  =  sum  of  excess  of  elevation  of  upper  terminals 
above  upper  terminal  of  main. 

7t  =  number  of  laterals  having  additional  head. 
C  =  depth  of  main  at  upper  end. 

Areas  Drained  by  a  Main. — The  number  of  acres 
that  a  main  is  to  actually  drain  is  not  the  only  element 
to  be  considered  in  this  connection,  but  the  manner  in 
which  the  water  is  to  be  brought  to  the  main,  together 
with  the  general  outline  and  contour  of  the  surface, 
should  also  be  carefully  investigated.  The  formula  i;-, 
based  upon  the  supposition  that  the  surface  of  the  tract 
is  reasonably  even,  and  that  the  drainage  is  brought  to 
the  main  by  lateral  tile  drains.  Should  a  main  be  laid 
through  a  watercourse  like  a  slough,  into  which  there 
is  considerable  lateral  surface  drainage  with  no  line? 
of  tile,  the  main  is  at  the  disadvantage  of  receiving  all 
of  its  water  along  one  narrow  line,  instead  of  taking  it 


FLOW   OF   WATER    THROUGH    PIPES.  I4I 

as  collected  by  a  series  of  laterals  and  brought  by  them 
to  various  points  along  its  course.  The  same  is  true 
of  many  drains  which  are  laid  into  ponds.  The  pond 
collects  surface  water  from  a  considerable  area,  and 
none  of  it  can  enter  the  drain  until  it  reaches  the  center 
of  the  pond. 

In  such  cases  and  many  similar  ones  which  occur 
in  practice,  the  acreage  should  be  converted  to  its 
equivalent  of  tile-drained  land  before  the  formula  is  ap- 
plied for  the  purpose  of  determining  the  size  of  drain 
which  should  be  used.  Find  the  area  of  the  land  which 
has  a  surface  slope  in  the  direction  of  the  drain,  and 
which  is  not  tiled,  add  one  half  to  the  area  if  in  gen- 
eral it  has  a  slope  of  2  or  3  to  100,  and  apply  the 
formula  to  the  corrected  acreage.  If  the  slope  is 
steeper,  the  acreage  should  be  increased  proportion- 
ally. For  example,  a  pond  through  which  a  drain 
passes  may  have  a  water-shed  of  six  acres,  but  may  slope 
toward  the  center  at  the  rate  of  2  or  3  per  100.  The 
drain  should  not  be  proportioned  for  six  acres,  but  for 
one  half  more,  or  nine  acres.  Mains  are  not  propor- 
tioned according  to  the  number  of  lines  of  tile  which  are 
to  discharge  into  them,  but  according  to  the  area  of 
land  from  which  they  must  take  the  drainage. 

Limitations  of  Size,  Grade,  and  Length  of  Drain. 

From  what  has  preceded,  it  will  have  doubtless  oc- 
curred to  the  reader  that  there  are  certain  limitations 
to  the  size  of  the  drain  used,  its  grade,  and  the  total 
length  of  the  line,  beyond  which  it  is  not  wise  to  go. 
In  formula  No.  2  the  denominator  of  the  second  num- 
ber represents  the  resistances  which  oppose  gravity. 


142  ENGINEERING   FOR    LAND   DRAINAGE.  ' 

If  the  sum  of  these  equal  gravity,  no  flow  takes  place. 
It  may  be  observed  in  this  connection,  by  way  of  ex- 
planation, that  head  is  considered  as  divided  into  two 
parts.  One  part  overcomes  friction,  and  is  called  fric- 
tion head,  the  other  generates  velocity  and  is  called 
velocity  head.  The  v  of  the  formula  is  the  mean 
velocity  of  actual  flow  from  the  tile  which  is  under  con- 
sideration, and  is  the  difference  between  the  friction 
head  and  the  velocity  head. 

Considering  the  fact  that  friction  is  greater  for  small 
tiles  than  for  large,  and  greater  for  long  drains  than 
for  short  ones,  and  that  the  velocity  decreases  as  the 
square  root  of  the  head,  it  is  easy  to  see  that  a  drain 
of  certain  size  may  be  laid  with  so  little  grade  and 
have  such  a  length  that  the  discharge  will  be  little  or 
nothing.  These  facts  will  appear  to  some  extent  when 
the  formula  is  used,  yet  it  will  be  best  to  observe  in  a 
general  way  the  following  limits: 

Table  6. 

LIMIT  OF  SIZE  OF  TILE  TO  GRADE  AND  LENGTH. 
Size  of  Tile  Minimum  Grade  Limit  of  Length 

in  Inches.  per  loo  Feet.  in  Feet. 

2 lo 6oo 

3 09 800 

4 05 1600 

5 05 2000 

6 05 2  500 

7 05 2800 

8 .05 3000 

9 05 3500 

10 04 „ 40CX) 

II. 04 4500 

12 04 530Q 


FLOW   OF   WATER   THROUGH   PIPES.  I43 

This  table  means  that  the  size  of  tile  given  should 
not  be  laid  on  a  less  grade  nor  in  lines  of  greater 
length,  when  laid  upon  that  grade,  than  is  given  oppo- 
site the  size.  If  the  formula  should  call  for  a  certain 
size  when  the  length  is  greater  than  this,  then  use  a 
larger  size  than  that  denoted  by  the  formula. 


CHAPTER   X. 
SIZE  OF  LATERAL  DRAINS. 

The  size  of  tile  that  are  to  be  used  on  a  drainage 
System  should  be  determined  only  after  all  of  the  data 
and  knowledge  to  be  obtained  regarding  the  land  is  at 
hand  and  all  of  the  grades  have  been  figured  out.  The 
following  hints  as  to  the  manner  of  taking  up  this  divi- 
sion of  the  work  may  be  observed  with  profit. 

If  there  are  both  mains  and  sub-mains,  find  how 
much  land  is  to  drain  through  the  outlet  of  the  main, 
and  also  how  great  an  area  will  be  drained  by  each 
one  of  the  sub-mains.  Determine  the  size  of  each  out- 
let by  the  formula,  observing  carefully  the  manner  of 
using  it.  Diminish  the  size  of  these  drains  up-stream 
according  to  the  area  to  be  drained  to  that  point,  taking 
into  account  also  the  grades  of  the  several  parts.  If 
the  grade  is  light  and  uniform  the  large  sizes  should  be 
continued  well  up  towards  the  source  of  the  drain. 
Each  water-shed  should  be  considered  carefully  by  itself 
and  the  several  basins  be  connected  with  each  other  by 
the  main  drain  so  that  the  whole  will  balance  and  work 
as  one  drain. 

Size  of  Tile  for  Laterals. — No  attempt  should  be 
made  to  make  the  capacity  of  intercepting  drains  equal 
the  combined  capacity  of  the  laterals  where  a  system 
of  thorough  drainage  is  employed.     The  size  of  laterals 

144 


DIGGING   A   DITCH   FOR   TWELVE-INCH   DRAIN-TILE. 

{To /ace  page  144.) 


SIZE    OF    LATERAL    DRAINS.  I45 

where  the  soils  are  open  and  permit  the  use  of  drains 
100  or  more  feet  apart  should  be  4-  and  5 -inch  tile, 
which  in  some  cases  may  be  diminished  to  3  inches  at 
the  upper  end.  For  drains  at  a  less  distance  apart 
3-inch  tile  may  be  used  for  laterals.  They  are  usually 
required  to  carry  only  a  small  part  of  their  full  capacity 
in  order  to  relieve  the  soil  of  its  surplus  water.  To  do 
this  well,  however,  they  should  not  be  quite  full  at  any 
time  unless  it  be  when  there  is  more  than  ordinary  rain- 
fall. They  do  not  work  under  a  pressure  head,  hence 
their  velocity  of  flow  is  as  great  when  running  half  full 
as  when  running  full.  Water  in  a  drain  attains  great- 
est velocity  when  three  fourths  full  and  its  greatest 
rate  of  discharge  when  nine  tenths  full. 

Should  the  system  of  laterals  have  a  heavy  grade 
compared  with  the  mains  into  which  they  discharge, 
the  mains  will  often  work  under  pressure  and  run  full 
when  the  rainfall  is  not  very  large.  They  will  of  course 
run  no  more  than  full  under  a  greater  head,  but  the 
velocity  and  discharge  will  be  greater.  It  is  often 
thought  that  since  a  main  drain  is  running  full,  it  is 
doing  all  that  it  is  capable  of  doing.  From  what  has 
been  said  above,  it  will  be  seen  that  this  is  not  the  case. 

Provision  for  Unusual  Rainfall. 

The  rules  thus  far  given  for  the  size  of  tile  do  not 
provide  for  the  carrying  off,  through  the  tile  system 
alone,  unusually  heavy  rainfalls  of  2  to  3  inches  in 
twenty-four  hours.  These  occur  sometimes  two  or  three 
times  a  year.  Again,  two  or  three  years  may  pass  with- 
put  witnessing  such  a  downpour.      It  is  still  more  rare 


146     ENGINEERING  FOR  LAND  DRAINAGE. 

that  these  excesses  come  at  a  season  of  the  year  when  a 
short  flooding  will  injure  growing  crops,  yet  these  facts 
should  all  be  taken  into  account  when  we  provide  a 
drainage  system.  There  are  two  difficulties  which  are 
encountered  in  providing  for  floods  with  tile  drains. 
The  first  is  that  there  are  many  soils  that  will  not  per- 
mit the  water  to  pass  through  them  rapidly  enough 
so  that  the  water  will  not  accumulate  upon  the  surface 
when  the  rainfall  is  sudden  and  large  in  quantity.  The 
second  is  that  the  tile  which  should  be  used  to  carry  it 
all  off  must  be  of  double  the  ordinary  capacity,  which 
involves  a  great  expense. 

In  general  land  drainage  it  will  be  found  wise  to  pro- 
vide for  the  excessive  rainfall  by  keeping  well-con- 
nected depressions  or  broad  shallow  open  ditches  along 
the  course  of  natural  drainage,  so  that  the  flood  water 
will  pass  off  over  the  surface  and  thus  relieve  the  un- 
der drains  of  the  excess.  In  level  lands,  where  there 
is  the  most  necessity  for  this  provision,  no  harm  will 
come  from  surface  washing,  for  as  soon  as  the  excess 
passes  ofl"  over  the  surface  the  remainder  of  the  drain- 
age passes  off  through  the  soil.  There  is  no  loss  of 
land,  since  in  most  cases  these  broad  depressions  or 
ditches  can  be  cultivated. 

Where  the  fall  is  very  considerable,  the  capacity  of 
the  underdrains  will  be  greatly  increased  by  reason  of 
the  grade  that  may  be  obtained  and  hence  there  will 
be  less  necessity  for  surface  drainage,  yet  this  part  of 
the  work  should  never  be  lost  sight  of. 

There  are,  however,  valleys  or  depressions  like  large 
ponds  or  swamps  for  which  it  is  impracticable  to  main- 
tain any  surface  drainage.     For  such  places  we  must 


LAYING   TWELVE-INCH  DRAIN-TILE. 


{To  /ace  page  146.) 


SIZE   OF    LATERAL   DRAINS.  I47 

increase  the  size  of  the  main  tile,  by  figuring  to  carry 
J  inch  of  water  in  twenty-four  hours,  thus  doubling  the 
size  that  would  otherwise  be  required. 

In  the  consideration  of  questions  relating  to  the  size 
of  drains,  and  provision  for  surface  overflow,  it  will  be 
seen  that  there  is  room  for  the  exercise  of  knowledge 
and  good  judgment,  and  it  may  be  added  for  the  in- 
formation of  those  who  are  sceptical  regarding  the 
value  of  the  care  thus  far  urged,  that  it  is  necessary  if  it 
is  expected  to  realize  the  best  results  from  the  drainage 
work. 

Selection  of  Tile. 

The  tile  selected  should  be  well  burned,  and  hard 
enough  to  give  a  clear  ring  when  struck.      They  should 
be  uniform  in  size,  so  that  each  size  can  be  laid  in  a 
smooth  and  continuous  line  without  ragged  projections 
on  the  inside.      The  approved  form  is  the  round  tile  I 
foot  long.      Sizes  larger  than  lo-inch  are  better  if  made 
24  inches  long.      There  are  many  different  qualities  of 
tile,  owing  to  the  variety  of  clays  that  are  worked  for 
this  purpose.      The  two  general  classes  are  known  as 
'*  red  tile"  and  **  vitrified  tile."     The  first  are  made 
of  common  clay  and  are  very  generally  used  for  farm 
work.     They  are  not  always  red  in  color,  but  are  not 
vitrified  and  come  under  the  general  class.     There  are 
comparatively  few  of  these  that  will  endure  alternate 
freezing  and  thawing  such  as  the  outlet  of  main  drains 
is  subject  to,  so  that  for  such  exposed  places  vitrified 
tile  should  be  substituted.     Many  of  them  will  not  en- 
dure the  exposure  of  the  winter,  when  placed  in  piles 
on   cultivated   land,    without   scaling   or  chipping  off. 


14^  ENGINEERING    FOR   LAND   DRAINAGE. 

When  placed  in  the  ground,  however,  they  are  durable 
and  in  every  way  satisfactory,  provided  they  are  well 
burned.  The  vitrified  tile  are  made  of  clay  which  will 
endure  such  heat  that  the  peculiar  elements  which  are 
a  part  of  their  composition  will  form  a  glassy  material 
which  is  hard  and  as  durable  as  the  best  quality  of 
stone.      They  are  always  desirable  drain-tile. 

The  manner  of  designating  the  size  is  by  naming  the 
inside  diameter,  as  4-inch,  6-inch,  meaning  tile  are  4 
inches  and  6  inches  inside  diameter  respectively.  They 
are  sold  by  the  thousand  feet  or  by  the  thousand  pieces, 
each  piece  supposed  to  be  I  foot  long. 

The  required  number  of  junction  tile  for  connecting 
the  several  laterals  with  the  mains  should  be  specified, 
as  the  practice  of  making  them  in  the  field  by  chip- 
ping and  breaking  the  tile  is  not  to  be  commended. 
The  Y  junction  in  preference  to  the  T  junction 
should  be  selected.  Curved  tiles,  such  as  are  used  in 
making  curves  in  sewers,  are  not  required  for  drains. 
The  turns  can  be  made  sufficiently  long  so  that  the 
ordinary  tile  can  be  used  if  care  is  taken  in  fitting  them. 
There  is  a  tendency  on  the  part  of  some  manufacturers 
to  make  the  walls  of  tiles  too  thin,  which  causes  them 
to  break  too  easily  in  handling.  The  following  is  a 
safe  minimum  thickness  for  the  walls  of  drain  tiles: 

3  inch J^inch 

4to  5     -   I     - 

6  and  7     ''    J     ** 

9     "   .• I     " 


10  and  12     ** tI  ** 

14  '*   I      ** 

15  ** ,  .  i^  inches 

18     ♦* : li      ** 


SIZE   OF   LATERAL   DRAINS. 


149 


Tabulating  Tile. 

After  the  engineer  has  determined  the  number  and 
size  of  the  tile  for  each  drain,  he  should  note  it  upon 
the  field-book  along  with  other  particulars  pertaining 
to  the  drain.  The  tile  of  the  whole  field  or  system 
should  then  be  tabulated,  an  example  of  which  is  given 
below,  in  order  that  a  bill  of  tile  according  to  size  can 
conveniently  be  made  out,  and  also  that  they  may  be 
distributed  in  the  field  without  confusion.  The  follow- 
ing plan  may  be  followed  in  making  this  list.  The 
last  column  gives  the  total  length  of  each  separate 
drain  and  should  be  used  in  checking  the  work. 

DISTRIBUTION  OF  TILE      (Example  of  Form.) 


Drain. 

i2-in. 

10-in. 

8-in. 

7 -in. 

6-in. 

5 -in 

4-in. 

Total. 

Main  A  .  , 

800 

1200 

250 

450 

200 

1300 

480 
1350 

IIOO 

300 

900 

600 

1260 

400 
600 

4680 
1350 

IIOO 

No.  I 

No.  2  

No.  3 

300 

No.  4 

3SO 

900 

740 
Soo 
200 

Branch  a  of  No.  4. . 

1500 

No.  s. . 

2000 

Main  B 

700 

400 

1600 

No.  I  of  B 

600 

No.  2  of  B 

600 

800 

1200 

9SO 

4SO 

9SO 

4090 

6990 

IS430 

SUMMARY. 

800 1 2-inch 

1200 10    ** 


950. 
450. 
950. 

4090. 
6990. 


15430 


CHAPTER  XL 
OPEN  DRAINS. 

Successful  tile  drainage  necessitates  the  construc- 
tion of  open  ditches,  unless  the  mains  are  so  situated  as 
to  discharge  into  natural  streams.  When  the  area  is  too 
great  to  be  drained  by  a  tile  main  whose  cost  will  be 
within  profitable  limits,  then  an  open  ditch  should  be 
used.  It  is  sometimes  difficult  to  determine  when  an 
open  ditch  should  take  the  place  of  tile  drain.  Usually 
where  the  cost  of  the  two  is  about  equal  the  tile  should 
be  used  provided  the  outlet  for  the  tract  will  be  just  as 
efficient.  However,  this  is  a  question  that  must  be  de- 
cided in  the  light  of  such  facts  and  considerations  as 
pertain  to  each  individual  case,  and  in  accordance  with 
sound  theory  and  safe  practice. 

It  is  proposed  to  discuss  this  matter  in  such  a  practi- 
cal way  that  what  is  said  may  be  of  use  to  the  young 
engineer  in  laying  out  and  constructing  large  open 
ditches  for  drainage  purposes,  not  in  a  guess-work  sort 
of  a  way,  but  according  to  the  best  knowledge  and  prac- 
tice now  existing. 

Grade  for  Open  Ditches, 

The  total  fall  across  a  tract  has  been  fixed  by  nature, 
but  it  is  the  work  of  the  engineer  to  determine  whether 
or  not  nature  has  provided  enough  for  his  purpose,  and 
to  adapt  the  size,  form,  and  cross-section  of  the  ditch 

150 


OPEN  DRAINS.  I5I 

to  the  available  grade.  The  fall  that  is  usually  found 
in  districts  where  it  is  necessary  to  construct  large  out- 
let channels  is  from  i  foot  to  5  feet  per  mile.  These 
are  the  main  channels  or  outlets  for  the  drainage  of 
large  areas.  Lateral  open  ditches  for  small  areas  and 
for  farms  have  usually  a  higher  rate  of  fall,  but  not 
always.  It  is  desirable  that  ditches  have  sufficient  fall 
to  be  self-cleaning.  This  in  soil  and  clay  which  is  not 
easily  displaced  is  about  4  feet  per  mile,  which  for 
ditches  of  ordinary  size  will  give  a  mean  velocity  of 
2f  miles  per  hour  when  running  full.  This  is  given 
as  an  approximate  grade  for  ditches  which  may  be  re- 
lied upon  as  self-cleaning,  and  applies  to  those  with 
bottoms  not  less  than  3  feet  wide  and  a  depth  not 
less  than  4  feet,  and  so  adjusted  in  size  that  they  will 
run  three  fourths  full  at  flood  height.  This  is  by  no 
means  the  minimum  grade  upon  which  effective  ditches 
may  be  constructed.  As  a  matter  of  fact  there  are  many 
large  tracts  of  land  drained  by  outlet  ditches  having  a 
fall  of  from  6  to  24  inches  per  mile.  These  are  not,  how- 
ever, self-cleaning  except  when  made  deep  and  large 
with  a  final  free  discharge,  and  even  then  a  liberal 
annual  allowance  should  be  made  for  cleaning.  As 
can  be  readily  understood,  there  can  be  but  little  or 
no  scouring  action  of  the  water  upon  the  bottom  of  the 
channel  unless  the  head  is  furnished  by  the  depth  of 
water  in  the  ditch.  Hence  light-grade  channels  must 
be  deep — 6  to  8  feet  if  possible— or  else  provision  must 
be  made  for  frequent  artificial  cleaning.  This  continual 
expense  will  in  the  course  of  ten  years  go  far  towards 
paying  the  additional  first  cost  of  a  deeper  ditch. 
Where  tracts  are  level  and  grades  light,  depth  of  ditch 


152     ENGINEERING  FOR  LAND  DRAINAGE. 

has  come  to  be  recognized  a  necessary  adjunct  of  suc- 
cessful drainage. 

Mean  Velocity  of  Flow, 

The  velocity  of  water  flowing  in  an  open  channel  is 
retarded  by  the  contact  of  the  particles  with  the  bottom 
and  sides  of  the  channel,  these  resistances  being  greater 
or  less  according  to  the  nature  of  the  material  through 
which  the  channel  is  dug  and  the  irregularities  pre- 
sented by  the  bottom  and  sides  and  having  contact 
with  the  water.  It  has  been  demonstrated  that  the 
films  of  water  from  the  bottom  of  the  channel  upward 
toward  the  surface  and  from  the  sides  toward  the  cen- 
ter of  the  channel  forrn  vertical  and  horizontal  curves 
respectively  with  the  advanced  portion  of  the  curves 
in  the  center  line  of  the  stream.  If  these  curves  were 
platted  the  resistance  of  the  sides  and  of  the  bottom  of 
the  ditch  would  have  the  appearance  of  holding  back 
the  water  so  that  no  two  films  of  water  would  have  the 
same  velocity.  The  greatest  velocity  of  a  stream  is 
found  in  the  thread  of  the  current  just  underneath  the 
surface,  all  other  parts  having  a  less  velocity  in  pro- 
portion as  they  approach  the  bottom  and  sides  of  the 
channel.  In  considering  the  discharge  of  a  channel  we 
must  use  the  mean  velocity  of  flow,  which  in  a  trape- 
zoidal earth  channel  is  about  eight  tenths  of  the  surface 
velocity,  and  is  the  velocity  found  at  a  point  in  the  cen- 
ter line  of  the  stream  and  a  little  more  than  half  way 
from  the  surface  to  the  bottom.  The  bottom  velocity 
is  about  seven  tenths  of  the  surface  velocity,  depending 
much  upon  the  kind  of  material  which  forms  the  bot- 
tom.    An  increase  in  the  depth  of  the  water  in  a  ditch. 


OPEN   DRAINS. 


153 


since  it  is  a  virtual  addition  of  head,  accelerates  the 
velocity.  The  following  table  shows  the  effect  that 
increase  of  depth  has  upon  the  mean  velocity  in  a' rect- 
angular channel  10  feet  wide  with  a  grade  of  3  feet  per 
mile. 

MEAN  VELOCITY  OP  WATER  AT    DIFFERENT  DEPTHS  IN   RECT- 
ANGULAR  DITCH  10  FT.  WIDE.  GRADE  3  FT.   PER  MILE. 


Depth  in  Feet. 

Mean  Velocity  in 
Feet  per  Second. 

0-5 
1.5 
2.0 

2.5 

3-0 
4.0 

It 

8.0 

1.4 

23 
2.6 
2.8 

2.9 

3-2 

Relation  of  Breadth  and  Depth  of  Channel  to  Surface 
and  Mean  Velocity. 
As  the  result  of  many  experiments  by  careful 
hydrauHcians,  the  following  table  from  ''Fanning's 
Hydraulic  Engineering"  may  be  given  to  show  the 
relation  of  breadth,  depth,  surface  velocity  and  mean 
velocity  to  each  other  for  rectangular  smooth  channels 
when  the  water  is  from  5  to  lO  feet  deep.  Let  b=z 
breadth,  d  —  depth,  V  =  surface  velocity  at  thread  of 
current,  and  v  =  mean  velocity. 

When  d  =     2d  then  v  =  .920  V, 


b  = 

W 

V    ::^ 

.910  V, 

b  = 

4  d 

V  — 

.896  V. 

b  = 

S  d 

V    = 

.882  y. 

b  = 

6d 

V    := 

.864  V. 

b  = 

7  d 

V   = 

.847  V. 

b  = 

8  d 

V   = 

.826  V. 

b  = 

qd 

V   = 

.80^  V, 

b  = 

10  d 

V  = 

.780  V. 

154  ENGINEERING   FOR    LAND   DRAINAGE. 

The  mean  velocity  will  be  a  little  less  for  a  trape- 
zoidal channel  and  will  decrease  as  the  side  slopes 
are  flattened.  When  the  breadth  is  twice  the  depth 
we  have  a  mean  velocity  of  flow  equal  to  92  per  cent 
of  the  surface  velocity  measured  in  the  middle  of  the 
channel. 

Curvature  of  Ditches, 

The  proper  curve  to  give  ditches  when  they  are  de- 
flected from  a  straight  line  is  a  matter  which  merits 
careful  attention.  It  is  desirable  that  the  adjustment 
of  curve  to  velocity  of  flow  be  such  that  the  banks  will 
not  require  artificial  protection.  The  relation  of  bank 
erosion  to  curvature  of  the  ditch  and  the  velocity  of 
flow  is  intricate  owing  to  the  great  difference  in  the 
stability  of  earth  when  subjected  to  the  action  of  water.     J 

Circular  curves  are  described  by  the  number  of  de-  ' 
grees  of  arc  which  a  chord  of  100  feet  subtends.  The 
degree  of  a  curve  is  determined  by  the  central  angle 
which  is  subtended  by  a  chord  of  100  feet.  For  curves 
of  from  I  degree  to  10  degrees  the  radius  may  be  found 
by  dividing  5730  feet  (the  radius  of  a  i -degree  curve) 
by  the  degree  of  the  curve.  The  following  is  a  list  of 
curves  and  their  corresponding  radii,  which  may  be 
used  as  a  basis  in  constructing  ditches  with  limitation 
as  hereafter  described : 

Degree  of  Radius  Degree  of  Radius 

Curve.  in  Feet.  Curve.  in  Feet. 

7° 819      14° 410 

8° 716      IS*. 383 


9° 637  16° 359 

10^ 574  17° 338 

II 522  18° 320 

12° 478  19°. 310 

13° 442  20° 288 


OPEN   DRAINS. 


155 


While  circular  curves  may  be  used  to  describe  ap- 
proximately the  curvature  that  should  be  given,  the 
true  form  should  not  be  geometrical,  but  rather  what 
may  be  termed  natural,  or  such  as  is  used  in  laying 
out  artificial  streams  and  roads  in  parks,  in  which  geo- 
metrical lines  are  ignored.  The  difference  between  the 
two  is  shown  in  Fig.  29,  which  is  a  12 -degree  curve 


Fig.  29. — Proper  Curve  for  Open  Ditches. 

(radius  478  feet)  varied  so  as  to  subject  the  bank  against 
which  the  stream  strikes  when  first  deflected  to  the 
least  possible  erosion.  The  reason  for  this  is  well  illus- 
trated by  Fig.  30,  in  which  the  stream  is  represented 
as  being  divided  into  filaments,  each  having  a  velocity 
imparted  to  it  by  the  flow,  and  striking  the  opposite 
bank  as  an  individual  force.  According  to  the  well- 
known  law  of  force,  the  angles  of  incidence  and  reflec- 
tion are  equal  when  a  force  meets  a  resisting  plane. 
Hence  in  the  case  under  consideration,  the  reflected 


156 


ENGINEERING    FOR   LAND   DRAINAGE. 


force  is  thrown  against  the  other  forces  or  filaments 
toward  the  interior  of  the  stream  and  assist  in  breaking 
the  force  and  deflecting  the  current.  The  section  of 
curve  first  struck  will  receive  the  greatest  force,  and  be 
subject  to  greater  erosion  if  the  curve  were  a  segment 


Fig.  30. — Action  of  Current  on  Ditch  Banks  at  Curves. 

of  a  circle.  For  this  reason  the  up-stream  part  of  the 
curve  should  be  deflected  from  the  tangent  by  using  a 
curve  of  greater  radius  than  the  remainder  of  the  curve, 
in  order  that  all  parts  may  be  subject  to  uniform  erosion. 

When  the  points  of  tangency  have  been  fixed  upon, 
the  curve  may  be  "  run  in  by  the  eye  "  better  than  by 
the  instrument,  and  the  center  line  located  by  measure- 
ments from  the  tangents  in  the  manner  shown  in  Fig.  29. 

How  short  a  curve  may  be  used  in  large  ditches  such 
as  are  constructed  for  drainage  districts  without  en- 
dangering the  stability  of  the  banks  at  the  curve  is  a 
question  that  cannot  be  answered  with  mathematical 
certainty  for  the  reasons  previously  stated.  Deduc- 
tions from  close  observations  of  both  natural  and  arti- 
ficial streams  which  flow  through  alluvial  soils  are  the 


OPEN  DRAINS. 


157 


only  guides  to  the  work.  From  such  observations  the 
following  empirical  rules  may  be  deduced : 

For  ditches  with  minimum  bottom  width  of  4  feet 
and  maximum  grade  of  2  feet  per  mile  use  20-degree 
curve  =  radius  of  288  feet.  For  ditches  with  bottom 
width  4  feet  to  8  feet  and  grade  of  3  feet  to  6  feet  per 
mile  use  12-degree  curve  =  478  feet. 

For  larger  ditches  and  greater  fall,  or  for  the  above- 
named  ditches  which  have  a  greater  fall  than  indicated, 
curves  ranging  between  6  degrees  and  12  degrees  may 
be  used  with  such  latitude  as  conditions  of  earth  and 
fall  may  indicate  to  the  careful  designer. 

Form  and  Depth  of  Ditches. 

The  foregoing  facts  have  an  important  bearing  in 
determining  the  form  that  should  be  given  to  a  ditch. 
A  channel  with  vertical  sides  offers  the  least  resistance 
to  the  current,  so  that  if  such  a  form  could  be  main- 
tained, it  would  carry  a  greater  volume  of  water  in  pro- 
portion to  its  cross-sectional  area  than  any  other  form. 
It  will  be  also  seen  that  the  velocity  is  greater  in  a  full 
channel  than  in  one  partly  full,  and  in  a  deep  channel 
running  full  than  in  a  shallow  one  running  full. 

It  follows,  then,  that  the  form  of  a  ditch  where  the 
fall  is  light,  and  where  it  is  desired  to  secure  the  best 
results  with  the  least  excavation,  should  approach  as 
near  as  possible  to  that  of  a  rectangle,  and  should  be 
as  deep  as  practicable.  Nothing  but  rocky  material 
will  stand  perpendicular.  Ordinary  clays  will  stand 
very  well  at  a  slope  of  45  degrees,  or  i  to  I  as  it  is 
called.  Loose,  loamy,  and  sandy  soils  will  sometimes 
require  a  side  slope  of  i  ^  to  i  in  order  to  stand  reason- 


^'N/J'i.o' l\ 


158  ENGINEERING   FOR   LAND   DRAINAGE. 

ably  well.  The  slope  that  is  preferable  in  ordinary- 
soils  is  that  of  I  to  I .  After  a  ditch  made  in  this  form 
has  been  in  use  a  year'  or  two,  the  action  of  the  water 
will  change  its  form,  the  upper  part  becoming-  more 
nearly  perpendicular  and  the  lower  more  nearly  hori- 
zontal. 

In  the  laying  out  of  ditches  for  the  drainage  of  large 
areas,  a  depth  of  from  5  to  7  feet  should  be  aimed  at 
for  two  reasons.  First,  this  depth  is  needed  for  the 
purpose  of  giving  good  lateral  drainage,  and  second, 
to  get  the  velocity  necessary  to  scour  the  bottoms  and 
make  them  self-cleaning  as  far  as  possible.  Broad  flat 
bottom  shallow  ditches  are  adapted  to  carry  floods  in 
freshet  times,  but  not  to  give  outlets  for  the  thorough 
drainage  of  level  tracts.  In  this  connection  it  may  be 
said  that  the  bottom  width  of  any  ditch  with  a  grade  of 
I  to  2  feet  per  mile  should  not  be  less  than  3  feet. 

Ditches  with  a  grade  of  lO  feet  per  mile  may  be 
made  with  any  bottom  width  which  will  furnish  the 
necessary  capacity.  Such  ditches  will  be  self-cleaning, 
and  often  precautions  must  be  taken  against  injury  of 
the  ditch  by  erosion.  The  side  slopes  must  be  gov- 
erned by  the  kind  of  soil  and  clay  through  which  they 
are  made,  and  also  by  the  means  that  are  to  be  used  in 
excavation.  If  the  work  is  to  be  done  with  teams,  a 
slope  of  about  2  to  I  must  be  given  to  the  sides.  If 
done  with  the  steam  dredge  it  can  be  made  with  slope 
of  I  to  I  or  less. 

Capacity  Required  for  Open  Ditches, 

How  large  a  drainage-channel  should  be  made  to 
afford  an   outlet  for  a  given  area  is  a  question  which 


OPEN   DRAINS.  1 59 

must  be  answered  at  the  beginning  of  every  drainage 
enterprise.  There  are  three  distinct  elements  that 
must  be  taken  into  consideration  in  deciding  this  matter. 

1.  Area  of  the  drainage-basin,  and  also  its  shape; 
that  is,  the  number  of  acres  that  will  be  drained  by  the 
ditch  when  made,  and  whether  this  area  lies  in  a  broad 
tract  on  either  side  of  the  proposed  ditch,  or  is  in  the 
form  of  a  narrow  strip  along  its  course. 

2.  Slope  of  the  land;  that  is,  whether  it  is  broken  up 
by  alternate  steep  slopes  and  flats  or  is  a  plane  having 
but  little  variation  in  level. 

3 .  The  fall  that  can  be  obtained  for  the  ditch  along 
the  various  parts  of  its  course. 

The  bearing  which  these  conditions  have  upon  the 
size  of  ditches  may  be  stated  in  a  general  way  as  fol- 
lows: If  the  tract  is  level  and  broad,  drainage-water 
will  be  held  back  a  longer  time  and  be  distributed  to 
the  main  ditch  much  more  slowly  than  if  the  tract  were 
narrow  and  has  steep  slopes  which  will  shed  water 
rapidly  toward  the  main.  If  the  surface  is  broken  up 
and  slopes  are  steep  the  soil  will  absorb  less,  and  the 
greater  surface  slope  will  impel  the  surplus  water  with 
greater  velocity  over  the  surface  toward  the  main  ditch, 
and  thereby  tax  its  capacity  more  than  if  the  land  were 
more  nearly  level. 

Quantity  of  Water  per  Acre  to  be  Removed. 

It  is  a  common  opinion  that  if  a  ditch  of  certain 
capacity  will  drain  a  given  area  that  it  will  require  a 
ditch  of  double  that  capacity  to  drain  twice  the  area. 
An  examination  of  natural  streams  and  their  water- 


l6o  ENGINEERING   FOR   LAND  DRAINAGE. 

sheds,  as  well  as  experience  with  artificial  ditches,  does 
not  sustain  this  opinion.  The  larger  the  area  the 
greater  the  proportion  of  drainage-water  which  is  held 
back  by  obstructions,  so  that  the  discharge  of  the  out- 
let ditch  for  a  given  time  is  not  so  great,  neither  is  the 
proportion  which  is  finally  discharged  as  great  for  large 
as  for  small  areas.  The  quantity  of  water  to  be  carried 
per  acre  is  greater  for  open  ditches  than  for  tile  drains, 
since  we  have  assumed  that  much  of  the  flood  water  is 
to  be  carried  by  surface  drains  in  the  case  of  large  tile- 
drained  areas,  and  hence  we  must  make  provision  for 
carrying  the  final  surplus  through  the  main  channels 
which  are  now  under  consideration. 

From  a  large  number  of  observations  upon  areas 
which  have  been  drained  by  ditches  whose  discharging 
capacities  were  known,  it  has  been  found  that  calcula- 
tions should  be  made  upon  the  following  basis,  in  which 
it  is  assumed  that  at  flood  time  the  main  ditch  is  to  run 
eight  tenths  full. 

Areas  from  looo  to  3000  acres,  with  lateral  fall  of 
land  toward  the  main  at  the  rate  of  2  to  3  feet  per  mile, 
remove  J  inch  in  depth  of  water  in  twenty-four  hours. 

Areas  3000  to  8000  acres  remove  ^  inch  in  depth 
in  twenty-four  hours. 

Areas  8000  to  30,000  acres  remove  J  inch  in  depth 
in  twenty-four  hours. 

If  the  land  is  rolling  so  that  considerable  areas  have 
slopes  of  I  to  3  or  more  feet  per  100,  the  above  figures 
should  be  increased  proportionally.  For  ordinary 
drainage  districts  the  ^-inch  standard  will  usually  ap- 
ply, understanding  that  very  heavy  rainfall  will  very 
nearly  fill  the  ditch. 


OPEN   DRAINS.  j6l 

Formula  for  Open  Ditches. 

The  force  which  impels  water  along  the  ditch  is  the 
rate  of  fall.  The  forces  acting  against  this  are  the  re- 
sistance offered  to  the  water  by  the  sides  and  bottom 
of  the  ditch.  The  difference  between  these  forces  is 
the  velocity  head  and  causes  whatever  current  there 
may  be  produced.  When  the  water  becomes  low  in  a 
ditch  which  has  slight  fall,  the  bottom  being  covered 
with  silt  or  overgrown  with  grass,  the  two  forces  balance 
and  there  is  no  flow. 

A  formula  used  for  velocity  of  flow  in  ordinary  drain- 
age-canals with  good  results  is  the  following: 


^  =  1/  ^  X  ij/.      .     .     .     (10) 

Q  =  av. 
Where  v  =  mean  velocity  in  feet  per  second. 
a  -=z  area  of  waterway. 

p  =  wet  perimeter  or  border  of  the  channel 
which  is  wet. 

/=  fall  in  feet  per  mile. 

Q  =  discharge  in  cubic  feet  per  second. 

This  formula  gives  results  sufficiently  close  for  the 
purpose.  It  must  be  remembered  that  in  applying  any 
of  the  drainage  formulas  the  data  at  hand  are  not  always 
of  the  most  accurate  kind,  and  there  must  be  a  margin 
allowed  for  contingences  that  cannot  be  provided  for 
by  means  of  definite  quantities  which  may  be  inserted 
in  a  formula. 

To  Apply  the  Formula. — Find  the  area  of  the  water- 
way of  the  proposed  ditch  in  square  feet  when  it  is 


1 62  ENGINEERING   FOR   LAND   DRAINAGE. 

filled  eight  tenths  full.  Find  the  length  of  channel 
which  is  wet  by  this  depth  of  water,  called  the  wet 
perimeter.  Find  the  fall  in  feet  per  mile  and  substi- 
tute the  quantities  thus  determined  in  the  formula  and 
find  the  value  of  v. 

To  find  the  number  of  acres  which  the  proposed 
ditch  will  drain,  proceed  as  directed  for  finding  the 
number  of  acres  which  a  tile  will  drain.  Find  the 
value  of  Q  and  divide  it  by  the  decimal  which  represents 
the  quantity  of  water  that  must  be  discharged  per  sec- 
ond in  order  to  relieve  the  land  of  the  desired  depth  of 
water  per  acre.     By  formula  the  expression  would  be 

A=.^ (n) 

A  =  number  of  acres,  n  =  number  taken  from  table 
No.  5. 

Example:  Given  a  ditch  with  bottom  8  feet,  fall  3 
feet  per  mile,  side  slopes  i  to  i,  water  to  run  5  feet 
deep  in  flood  time,  how  many  acres  will  it  give  an 
outlet  for  using  the  ^-inch  standard? 

^  =  13  X   5  =  65. 

/  =  8  -f  2   V2S  +  25  =  22.14. 

I  J/  =  4. 5.      Substituting  in  the  formula 


v=    |/^ 


22.14x4-5  =  3.63, 

g  ==  65  X  3.63  =  235.9  =  cu.  ft.  disch.  per  sec, 

.        235.9 

A  =  -^i^i-^  =z  11,233. 
.0210  '   *^-^ 

With  a  fall  of  2  feet  per  mile  A  =  9183. 
«<    <*    '<    ''    I  foot     "      *'    A  =  6914. 


OPEN   DRAINS. 


163 


The  following  examples  of  ditches  of  different  sec- 
tions and  rates  of  fall,  with  computations  for  velocity, 
discharge,  and  number  of  acres  which  they  will  drain 
(Fig.    31),    will   serve  to   show  the  method  of  using 

(1)  Fall  2  ft.  per  Mi. 


Fig.  31. — Data  required  for  Computing  Discharge  and  Acreage  Drained 
by  Ditches. 

formula  (10).  This  method  of  determining  the  num- 
ber of  acres  for  which  a  ditch  will  give  an  outlet  is 
given  because  it  is  based  on  correct  principles,  is 
simple  of  application,  and  has  been  found  applicable 
to  level  tracts  of  land.  Its  adaptability  to  lands  of 
different  slopes  with  a  variety  of  contour  lies  in  the 


164  ENGINEERING   FOR   LAND    DRAINAGE. 

use  of  the  different  standards  for  the  quantity  of  water 
that  it  is  desired  to  remove.  For  example,  if  the  tract 
through  which .  the  ditch  passes  is  rolHng,  so  that  the 
lateral  drainage  is  brought  to  the  main  ditch  more 
rapidly  than  is  indicated  by  the  fall  of  the  main,  there 
is  a  greater  run-off  in  a  given  time,  and  hence  the 
higher  rate  of  discharge  must  be  used  in  computing  the 
number  of  acres  that  a  ditch  will  serve.  A  more  elab- 
orate hydraulic  formula  more  correct  theoretically 
would  require  a  greater  refinement  of  data  than  can 
usually  be  obtained  for  such  work  within  reasonable 
cost  limits 

(I) 


v=  j/l 


1. 81 

X  3  =  2.81, 


19.56 

145.6 
Q  =  145-6,  A  =  -^^  =  6931, 

162.4 
Q  =  162.4,  A  =  -^^  =  7733, 

(3) 


"  =  "^liS  ^  3  =  3-18, 

277.8 
Q  =  277.8,  A  =  ~^^  =  13223. 

(4) 


"  =  ^-^2  X  '-5  =  2-73. 

524 

Q  =  524,  ^  =  :5ii  =  25000. 


OPEN   DRAINS.  1 6$ 

Waste  Banks  and  Berm, 

The  waste  banks  from  the  large  ditches  often  be- 
come a  serious  inconvenience  in  the  cultivation  of  fields, 
and  where  the  work  is  done  by  the  steam-dredge  their 
reduction  to  suitable  proportions  for  farming  purposes 
is  a  matter  which  will  require  time  as  well  as  labor. 
The  earth  is  deposited  in  a  wet  and  plastic  condition, 
and  if  it  contains  no  sand  or  gravel  becomes  exceed- 
ingly hard  and  tough  when  dry  or  partially  dry.  It 
resists  all  efforts  that  may  be  made  to  spread  or  smooth 
the  irregular  heaps.  Nothing  but  exposure  to  the 
weather  will  so  disintegrate  the  mass  that  it  can  be 
graded  or  scraped  back  from  the  ditch.  A  due  regard 
for  economy  will  dictate  that  the  work  of  reducing  the 
waste  banks  shall  be  done  gradually,  as  the  action  of 
sun  and  rain  and  frost  may  open  and  pulverize  the  sur- 
face. The  waste  banks  also  form  a  dike  or  barrier  on 
each  side  of  the  ditch,  which  prevents  the  water  of 
drainage  depressions  along  the  course  from  entering 
the  ditch.  Breaks  or  openings  should  be  left  during 
construction  at  those  depressions  which  may  subse- 
quently be  required  to  perfect  lateral  surface  drainage. 
It  is  always  preferable  to  keep  a  strip  of  land  lo  feet 
wide  on  each  side  of  the  ditch  seeded  to  grass,  as  this 
will  secure  the  banks  by  reason  of  the  turf  and  also 
prevent  the  surface  run-off  along  the  edge  of  the  ditch 
from  carrying  loose  earth  into  it. 

The  width  of  berm  or  clear  space  between  the  edge 
of  the  ditch  and  the  waste  bank  is  important.  The- 
weight  of  the  excavated  earth  should  be  so  far  away 
that  the  sides  of  the  ditch  when  saturated  with  water 


l66  ENGINEERING    FOR   LAND   DRAINAGE. 

will  not  give  way  and  slide  by  reason  of  the  superin- 
cumbent weight.  A  distance  of  7  feet  from  the  outer 
edge  of  the  ditch  to  the  inner  edge  of  the  waste  bank 
will  be  sufficient,  yet  more  than  this  will  make  the 
after  working  down  of  the  waste  bank  more  convenient. 

Surveys  for  Open  Ditches, 

After  having  done  the  necessary  preliminary  topo- 
graphical work  for  the  purpose  of  determining  in  a  gen- 
eral way  where  the  ditch  or  ditches  should  be  located, 
the  lines  should  be  surveyed,  the  grades  established, 
and  the  quantities  of  earth  to  be  excavated  computed. 
The  first  work  is  to  run  the  center  line  of  the  ditch, 
which  is  done  in  the  manner  described  for  running  a 
line  for  a  tile  drain.  Stakes  should  be  set,  levels 
taken,  and  the  line  located  for  mapping  purposes  as 
heretofore  described. 

Locating  the  Grade. — The  most  satisfactory  method 
of  determining  upon  a  suitable  grade  for  a  long  line  is 
to  first  make  a  profile  upon  profile  paper,  which  will 
show  to  the  eye  the  relation  of  different  points  along 
the  line  with  respect  to  their  elevations.  Draw  trial 
grade  lines  upon  this  profile  in  pencil  until  one  is  found 
which  will  give  a  desired  fall  and  depth  to  the  several 
sections  of  the  ditch.  Then  run  this  in  on  the  notes 
and  compute  the  cuts  as  directed  for  tile  drains.  If 
the  line  is  short,  say  a  mile  long,  the  grade  may  easily 
be  fixed  in  the  manner  described  for  tile  drains.  In 
considering  the  matter  of  grade  and  depth,  it  should 
always  be  found  whether  or  not  all  of  the  land  that  it 
is  desired  to  drain  can  be  well  drained  through  the 


OPEN   DRAINS.  1 6/ 

proposed  ditch,  and  if  not,  whether  the  grade  and  depth 
can  be  so  adjusted  as  to  furnish  the  desired  outlet. 
These  points  can  be  determined  by  comparing  the  ele- 
vations furnished  by  the  topographical  survey  if  one  has 
been  made.  If  such  a  survey  has  not  been  made,  lev- 
els should  be  run  out  from  the  main  line  to  all  doubtful 
points.  At  the  time  the  survey  of  the  center  line  is 
made,  "bench-marks"  should  be  fixed  at  convenient 
places  not  far  from  the  line,  to  which  reference  can  be 
made  in  testing  the  ditch  during  and  after  construc- 
tion. The  most  permanent  are  made  on  the  brace 
roots  of  trees  into  which  a  notch  is  cut.  Usually,  how- 
ever, solid  hub  stakes  driven  firmly  into  the  ground 
at  out-of-way  points  must  be  used.  They  should  be 
driven  flush  with  the  surface  and  described  in  the  notes 
after  being  marked  by  some  guide-post  or  stake,  by 
which  they  may  be  located. 

Cross-sectioning. — Having  established  a  grade,  fig- 
ured the  center  cut,  and  decided  upon  the  size  and  form 
of  the  ditch,  proceed  to  set  the  slope  stakes  which  will 
define  the  top  width  of  the  ditch  and  to  take  such  levels 
as  may  be  necessary  to  properly  compute  the  required 
excavation. 

Where  ditches  are  made  through  level  tracts  and  no 
deductions  are  to  be  made  for  ditches  already  existing, 
the  distance  out  from  the  center  may  be  measured  di- 
rect and  a  level  taken  at  the  side  for  a  guide  in  con- 
struction. In  case  the  ground  is  more  or  less  uneven, 
the  setting  of  slope  stakes  is  a  necessary  part  of  the 
work  for  both  construction  and  computation  purposes. 

The  following  is  a  convenient  form  for  taking  and 
keeping  all  of  the  necessary  notes.     Th^  center  line  is, 


1 68 


ENGINEERING  FOR   LAND   DRAINAGE. 


supposed  to  have  been  run  first  and  computed  and  the 
necessary  blank  lines  left  for  the  subsequent  cross- 
section  work. 


FORM  OF  NOTE-BOOK  FOR  OPEN-DITCH  SURVEYS. 


Sta. 

+  s. 

H.I. 

-s. 

Elev. 

G.L. 

c. 

Cut. 

R. 
Cut. 

L. 
Cut. 

Distance 
Out. 

Cu. 

Yds. 

R. 

L 

O 

Sr.:: 

I- 

::: 

::: 

::: 

... 

::: 

::: 

::: 

::: 

Knowing  grade,  center  cut,  bottom  width,  and  side 
slopes,  set  up  the  instrument  and  obtain  the  H.  I.  from 
center  hub  or  from  the  nearest  bench-mark.  If  the 
ground  is  level  each  side  of  the  center,  the  distance  out 
from  the  center  for  slope  of  i  to  i  will  be  ^  bottom 
width  plus  center  cut,  for  slope  of  i|^  to  i  will  be  J 
bottom  width  plus  i^  times  center  cut,  etc.  For 
ground  higher  or  lower  than  the  center,  take  a  level 
at  an  estimated  distance,  find  elevation,  subtract  from 
it  the  grade-line  elevation  and  obtain  cut.  Use  this 
cut  instead  of  the  center  cut  as  above  described,  and  if 
the  computed  distance  out  corresponds  with  that  meas- 
ured, drive  the  slope  stake  and  record  the  cut  and 
distance  out  in  their  proper  place  in  the  book.  If  not, 
move  the  rodman  out  or  in  until  the  proper  point  has 
been  found.  The  rodman  measures  the  distance  out 
with  his  rod  and  drives  the  stakes  as  directed.  It  is 
good  practice  to  set  a  side  hub  on  the  right-hand  side 
for  the  use  of  the  contractor  while  constructing  the 
ditch,  since  the  centers  must  all  be  destroyed,  but  a  side 


OPEN   DRAINS.  1 69 

stake  can  be  preserved  for  reference  at  any  time.  The 
center  and  side  cuts  and  distance  out  when  recorded  in 
the  notes  furnish  the  data  required  for  computing  the 
excavation.  If  the  ground  is  very  irregular,  a  suffi- 
cient number  of  sections  must  be  taken  to  enable  the 
engineer  to  compute  the  contents  within  reasonable 
limits  of  accuracy. 

The  slope  stakes  having  been  set,  the  contractor 
may  begin  excavation  at  the  limit  indicated  by  them 
and  carry  the  required  slope  to  the  required  depth,  at 
which  depth  the  ditch  will  have  the  width  designated. 

Computing  the  Cubic  Yards  of  Excavation. — In 
the  usual  class  of  work  required  for  drainage  canals  it 
is  not  necessary  to  use  the  lengthy  and  inconvenient 
method  of  computing  earthwork  by  the  prismoidal 
formula.  However,  in  very  rough  ground  it  should  be 
used.  This  may  be  stated  as  follows :  From  the  notes 
compute  the  end  areas  of  a  100-foot  section  or  station, 
from  these  construct  the  middle  area.  Add  to  four 
times  the  middle  area  the  area  of  end  sections  and 
take  one  sixth  of  the  product  for  the  mean  area.  Frac- 
tional parts  of  a  station  should  be  treated  in  the  same 
manner  if  the  field  notes  have  been  taken  for  that  pur- 
pose. The  method  by  end  areas  is  as  follows:  Add 
the  end  areas  of  any  given  station  and  divide  by  two 
and  the  result  is  the  mean  area.  This  in  either  of  the 
above  methods  when  multiplied  by  the  length  of  sta- 
tion and  divided  by  27  will  give  the  number  of  cubic 
yards  in  the  station.  The  work  may  be  very  much 
shortened  by  the  use  of  the  following  table : 


I/O 


ENGINEERING   FOR    LAND   DRAINAGE. 


Table  7. 
excavation  tables. 


ii 

0.00 

0.10 

0.20 

0.30 

0.40 

0.50 

0.60 

0.70 

0.80 

0.90 

o 

0.00 

0.37 

0.74 

I. II 

1.48 

1.85 

2.  22 

2.59 

2.96 

3  33 

I 

3.70 

4.07 

4.45 

4.81 

5-19 

5. 56 

5 .  93 

6.30 

6.67 

7.04 

2 

7.41 

7.78 

8.15 

8.52 

8.89 

9.26 

9.63 

10.00 

I0.37 

10  74 

3 

11. Tl 

11.48 

11.85 

12.22 

12.59 

1 2 .  06 

13-33 

13.70 

14.07 

14.44 

4 

14.82 

15.19 

15.56 

15.93 

16.30 

16.67 

17.04 

17.41 

17.78 

18  15 

s 

18.52 

18.80 

19.26 

19.63 

20.00 

20.37 

20.74 

21 .  11 

21.48 

21.8s 

6 

22.22 

22.59 

22.96 

23.33 

23.70 

24.07 

24.44 

24.82 

25.19 

25-56 

7 

25-93 

26.30 

26.67 

27.04 

27-41 

27.78 

28.15 

28.52 

28.89 

29.26 

8 

29.63 

30.00 

30.37 

30.74 

31-J1 

31.48 

31.85 

32.22 

32.59 

32.96 

9 

33.33 

33-70 

34.07 

34.44 

34-82 

35.  '9 

35.56 

35-93 

36.30 

36.67 

lO 

37.04 

37.41 

37.78 

38.15 

38.52 

38.89 

39-  26 

•39-63 

40.00 

40.37 

II 

40.74 

41. 1 1 

41.48 

41-85 

42.22 

42.59 

42.96 

43-33 

43.70 

44-07 

12 

44.44 

44.82 

45.19 

45.56 

45-93 

46.30 

46.67 

47-04 

47.41 

47.78 

13 

48.15 

48.52 

48.89 

49.26 

49-63 

50.00 

50.37 

50.74 

51.11 

51-48 

14 

51  85 

52.22 

52.50 

52.06 

53.33 

53.70 

54-07 

54-44 

54-82 

55.19 

IS 

55.56 

55.93 

56.30 

56.67 

57-04 

57.41 

57.78 

58-15 

58-52 

58.80 

16 

59.26 

59.63 

60.00 

60.37 

60.74 

61.11 

61.48 

61.85 

62.22 

62.59 

17 

62  .06 

63.33 

63.70 

64.07 

64.44 

64.82 

65-19 

65.56 

65-93 

66.30 

18 

66.67 

67.04 

67.41 

67.78 

68.15 

68.52 

68.89 

60.26 

69.63 

70.00 

19 

70.37 

70.74 

71.11 

71.48 

71-85 

72.22 

72.59 

72.06 

73-33 

73.70 

20 

74.07 

74.44 

74.82 

75.19 

75-56 

75-03 

76,30 

76.67 

77.04 

77.41 

21 

77.78 

78.  l-? 

78.52 

78.80 

70-  26 

79-63 

80.00 

80.37 

80.74 

81. II 

22 

81.48 

81.85 

82.22 

82.50 

82.06 

83-33 

83-70 

84.07 

84-44 

84.82 

23 

85.  TO 

85.56 

85.93 

86.30 

86.67 

87.04 

87-41 

87-78 

88.15 

88.52 

24 

88.89 

89.26 

89-63 

00.00 

90.37 

90.74 

91. II 

91-48 

91.85 

92 .  22 

25 

92.59 

92.96 

93-33 

93.70 

94-07 

94-44 

94-82 

95-19 

95.56 

95.93 

26 

96.30 

96.67 

97-04 

97.41 

97.78 

98.15 

98-52 

98.89 

99.26 

99.63 

27 

100.00 

100.37 

100.74 

101 . 1 1 

101 .48 

101.85 

102. 22 

102.59 

102.96 

103.33 

28 

103.70 

104.07 

104.44 

104.82 

105.10 

105.56 

105.93 

1 06 . 30 

106.67 

107.04 

29 

107.41 

107.78 

108.15 

108.52 

108.80 

109.26 

109.63 

110.00 

110.37 

110.74 

30 

III. II 

I  I  I. 48 

III. 8'; 

112.22 

112.59 

112.96 

113.33 

113.70 

114.07 

114.44 

31 

114. 81 

115.18 

115.56 

115.92 

116.20 

116.67 

117.03 

117-40 

117.77 

118.15 

32 

118.52 

118.89 

119.26 

119-63 

120.00 

120.37 

120.74 

121 . II 

121 .48 

121.8s 

33 

122.22 

122.50 

122.96 

123.33 

123.70 

124.07 

124.44 

124.81 

125.18 

125.55 

34 

125.02 

126.30 

126.66 

127.03 

127.40 

127.77 

128.14 

128.51 

128.88 

120- 26 

35 

129.63 

130.00 

130.37 

130.74 

131 . 11 

131.48 

131.85 

132.22 

132.59 

132.06 

36 

133.33 

133.70 

134.07 

134-44 

134.81 

135.18 

135.55 

135-92 

136.29 

136.67 

^l 

137.04 

137.41 

137.78 

138.15 

138.52 

138.89 

139.26 

130-63 

140.00 

140.37 

38 

140.74 

141.11 

141.48 

141-85 

142.22 

142.59 

142.96 

143-33 

143.70 

144.07 

39 

144.44 

144.81 

145.18 

145-55 

145.92 

146.29 

146.66 

147-03 

147.40 

147.78 

40 

148.1^ 

148.52 

148.89 

149-26 

149.63 

150.00 

150.37 

150-74 

151  .11 

151.48 

41 

151.85 

152.22 

152.59 

152-96 

153.33 

153.70 

154.07 

154-44 

154.81 

155.18 

42 

155.55 

155.92 

156.29 

156.66 

157.03 

157.40 

157.77 

158.14 

158-51 

158.80 

43 

150-26 

159.63 

160.00 

160.37 

160.74 

161 . II 

161 .48 

161.85 

162. 22 

162  59 

44 

162 . 06 

163.33 

163.70 

164.07 

164.44 

164.81 

165.18 

165-55 

165.92 

166.30 

45 

166.67 

167.04 

167.41 

167.78 

168.15 

168.52 

168.89 

169. 26 

169.63 

170.00 

46 

"70.37 

170.74 

171.11 

171.48 

171.85 

172.22 

172.59 

172.96 

173.33 

173-70 

47 

174.07 

174.44 

174.81 

175-18 

175.55 

175.92 

176.29 

176.66 

177.03 

177-41 

48 

177.78 

178.15 

178.52 

178.89 

179.26 

179.63 

180.00 

180.37 

180.74 

181.11 

49 

181.48 

i8i.8s 

182.22 

182.59 

182.06 

183.33 

183.70 

184-07 

184.44 

184.81 

50 

185.18 

185.55 

185.92 

186.29 

186.66 

187.03 

187.40 

187.77 

188.14 

188.52 

51 

188.80 

189.26 

189.63 

190.00 

190.37 

190.74 

191 . 11 

191.48 

191.85 

102. 22 

52 

192.59 

192 .96 

193-33 

193-70 

194-07 

194-44 

194-81 

105. 18 

195-55 

195  93 

53 

196.30 

196.67 

197.04 

197-41 

197.78 

198. IS 

198.52 

108.80 

199-26 

199.63 

54 

200.00 

200.37 

200.74 

201 . 11 

20T .48 

201.85 

202 . 22 

202.59 

202.96 

203.33 

55 

203.70 

204.07 

204.44 

204,81 

205 . 18 

205.5s 

205.92 

206. 29 

206.66 

207.03 

56 

207.41 

207.78 

208. 15 

208.52 

208.80 

209.26 

200.63 

210.00 

210.37 

210.74 

57 

211 .  11 

211.48 

211.8'^ 

212. 22 

212.50 

212.06 

213.33 

213.70 

214.07 

214-44 

58 

214.81 

215.18 

215.55 

215.92 

216.20 

216,66 

217.03 

217.40 

217.77 

218.15 

OPEN   DRAINS. 


171 


Table  7 — Continued. 


218 
222 

225 
229 

237 
240 
244 
248 
251 
255 

259 
262 
266 
270 
274 
277 
281 
285 
288 
292 
296 
300 
303 
307 
311 
314 
318 
322 
325 
329 

337 
340 
344 
348 
351 
355 
359 
362 
366 
370 
374 
377 
381 
385 
388 
392 
396 
400 
403 
407 
411 
414 
418 
422 
425. 
429 
433 
4<7- 
440 


218. 
222. 
226. 
230. 
233. 
237. 
241. 
244. 
248. 
252. 
255- 
>59- 
2f)3- 
267. 
270. 
274. 
278. 
281. 
285. 
289. 
292. 
290. 
300. 
304. 
307. 
311. 
315- 
318. 
322. 
326. 
330. 
m- 
337. 
341. 
344- 
348. 
352. 
355. 
359- 
363. 
367. 
370. 
374. 
378. 
381. 
385. 
389. 
392. 
396. 
400. 
404. 
407, 
411. 
415- 
418. 
422. 
426. 
430. 
433. 
437. 
441. 


219. 

222  . 

226. 

230. 

234. 

237- 

241. 

245- 

248. 

252. 

256 

260. 

263. 

267. 

271. 

274. 

278. 

282. 

285. 

289. 

293- 

297. 

300. 

304. 

308. 

311- 

315. 

319- 

322. 

326. 

330. 

334. 

337. 

341  • 

345- 

348. 

352. 

356. 

360. 

363. 

367. 

371. 

374- 

378. 

382. 

385. 

389. 

393- 

397- 

400. 

404. 

408. 

411. 

415. 

419- 

422. 

426. 

430. 

434- 

437. 

441. 


219 
223 
227 
230 
234 
238 
241 
245 
249 
252 
25& 

2()0 
264 
2f)7 
271 
275 
278 
282 
286 
290 
293 
297 
301 
304 
308 
312 
315 
319 

327 
30 

334 
338 
341 
345 
349 
352 
356 
360 
3f)4 
367 
371 
37  5 
378 
382 
386 
390 
393 
397 
401 
404 
408 
412 
415 
419 
423 
427 
430 
434 
438 
441 


220 
223 
227 
231 
234 
238, 
242, 
245. 
249 
253 

2S7. 

260, 
264, 

268, 
271 
275 
279 
282 

28f), 

290 

294 
297 

301 
305 
308, 
312 
316. 

320 

323 
327 
331 

334 
338, 
342 
345 
349 
353 
357 
360, 
364 
368, 
371 
375. 
379 
382, 
386, 
390 
394 
397. 
401. 
405. 
408, 
412, 
416, 
420. 
423. 
427, 
431. 
434. 
438. 
442. 


220. 
224. 
227. 
231  - 

■2.>,$  . 
238. 
242. 
246. 
250. 

2  53- 
2S7. 
261. 
264. 

2f)8. 

272. 

^75- 
279. 
283. 
287. 
290. 
294. 
298. 
301  . 
305. 
309- 
312. 
316. 
320. 
324- 
327- 
331. 
335. 
338. 
342. 
346. 
350. 
353- 
357- 
3b  1. 
364- 
368. 
372. 
375- 
379- 
383. 
387. 
390. 
394- 
398. 
401. 
405- 
409. 
412. 
416. 
420. 
424. 
427. 
431- 
435. 
438. 
442. 


0.60 


220 
224 
228 
231 
235 
239 
242 
246 
250 
254 
257 

2(31 
265 
268 
272 
276 
280 
283 
04  287 


291 
294 
298 
302 
305 
309 
313 
317 
320 
324 
328 
331 

335 
339 
342 
346 
350 
354 
357 
361 
365 
368 
372 
376 
380 
383 
387 
391 
394 
398 
402 
40  s 
409 
413 
417 
420 
424 
428 
431 
435 
439 
442 


221 . 
224, 
228. 
232, 
235- 
239. 
243. 
247. 
250. 
254 
2=;8, 
261  . 

2f)5 

269 
272, 
276, 
280. 
284, 
287, 
291, 
295 
298, 
302, 
306 
310 
■33   313 


317 
321 
324 
328 
332 
335 
339 
343 
347 
350 
354 
358 
361 
365 
369 
372 
376 
380 
384 
387 
39T 
395 
398 
402 
406, 
410, 
413. 
417 
421. 
424 
428, 
432. 
435. 
439. 
443  • 


.80 


221 
225 
228 
232 
236 
240 
243 
247 
251 
254 
2=;8 
262 
265 
269 
273 
277 
280 
284 


29 
295 
299 
302 
306 
3 

314 
317 
32 
325 
328 
332 
336 
339 
343 
347 
351 
354 
358 
362 
365 
3'^9 
373 
377 
380 
384 
388 
391 
395 
399 
402 
406 
410 
414 
417 
421 
425 
28 
432. 
436. 
440. 
443- 


48  221.85 
225.55 
88  229.26 
59  232.96 
29  236.67 
00  240.37 
70  244.07 
247.78 
251  48 
2';5.i8 
52  258.89 
22  262.59 
92  266.30 
63  270.00 
273-70 
277.41 
281. II 
284.81 
288.52 
292.22 
29503 
299.63 
303-33 
307.03 
310.74 
314.44 
318.15 
321.85 
325.55 
329.26 
332.96 
336.67 
340.37 
344.07 
347.78 
351.48 
355.18 
358.89 
362.59 
366.30 
370.00 
373.70 
377-41 
381.11 
384-81 
388.52 
392.22 
395-92 
399-63 
403.33 


67  407.04 
37  410.74 
07  41444 
78  418.15 
48  421.85 
18  425.56 
89  429.26 
59  432.96 
29  436.67 
00  440.37 
70  44407 


1/2 


ENGINEERING   FOR   LAND   DRAINAGE. 


Table  7 — Continued. 


1 20 

121 
122 
123 
124 
125 
126 
127 
128 
129 

131 
132 
133 
134 
135 
136 

138 
130 
140 


444. 
448. 
451. 

455- 
459. 
462. 
466. 
470. 
474- 
477. 
481. 
485- 
488. 
492. 
496. 
500. 
503- 
507. 
511- 
5x4- 
^18. 


444. 
448. 
4!?  2. 
455- 
459- 
463- 
467. 
470. 
474. 
478. 
481. 
485. 
489. 
492. 
406. 
500, 
504, 
507. 
511. 
515. 
518, 


445. 
448, 
452. 
456. 
460. 
4(>3- 
467. 
471- 
474. 
478. 
482. 
485. 
489. 
493- 
497. 
500. 
504. 
508. 
Sii. 
515. 
S19 


0.30. 


445 
449 
452 
456 
460 
464 
467 
471 
47  5 
478 
482 
486 
490 
493 
497 
501 
S04 
508 
512 
51S 
519 


52 


0.40 


445. 
449- 
453. 
4'?7. 
460. 
464. 
468, 
471. 
475. 
479. 
482 
486, 
490. 
494 
497 
SOI 
505. 
508 
512 
S16 
520, 


446. 
450, 
453- 
457. 
461 . 
464, 
468. 
472. 
475. 
479 
483. 
487. 
490 
494 
498, 
501 
505. 
S09 
512 
516, 
520 


0.60 


446. 
450. 
454- 
457- 
461 . 
465. 
468. 
472. 
47ft. 
480. 
483. 
487. 
491. 
494- 
498. 
502. 
505. 
509. 
513. 
517- 
520. 


0.70 


447. 
450. 
454. 
458 
^bi  . 
465. 
469 
472 
476, 
480, 
484 
487 
49  r 
495 
498 
502 
506 
510 
513 
517 

521 


80 


447. 

451. 

454- 

458. 

462. 

4f>5. 

469. 

473 

477 

480. 

484 

488 

491 

495 

499 

502 

506 

510 

514 

S17 

521 


447.78 
451-48 
455.18 
458.89 
462.59 
466.30 
470.00 
47,5  70 
477.41 
481. II 
484  81 
488.52 
492.22 
495.93 
499.63 
503.33 
507.04 
510.74 
514.44 
518.15 
521.8s 


To  find  the  number  of  cubic  yards  from  Table  7,  turn 
to  the  left-hand  column  and  find  the  corresponding  area 
number.  Opposite  this  will  be  found  the  number  of 
cubic  yards  in  a  length  of  100  feet.  If  the  area  has  a 
decimal  part  pass  the  eye  to  the  right  and  take  the 
number  of  yards  in  the  column  under  the  decimal  cor- 
responding to  the  one  required.  If  the  number  of 
yards  for  a  part  of  a  station  only  is  required  take  such 
a  part  of  the  tabular  number  given  as  the  required 
length  is  of  100  feet. 

Examples:  The  mean  area  for  a  1 00-foot  section  is 
46.  How  many  cubic  yards  of  excavation  ?  Find  46 
in  the  left-hand  column,  and  opposite  is  170.37,  the 
number  of  cubic  yards. 

Suppose  the  mean  area  of  a  100-foot  length  is  60.7, 
find  60  in  the  left-hand  column.  Pass  the  eye  to  the 
right  and  in  the  column  headed  .70  take  224.81,  the 
number  of  cubic  yards  in  the  station.     As  the  several 


OPEN   DRAINS.  173 

stations  are  computed,  enter  the  results  in  the  note- 
book opposite  the  respective  stations,  and  in  the  column 
headed  for  that  purpose. 

Ditching  with  Steam  Dredges. 

As  large  ditches  can  be  made  more  profitably  with 
the  steam  dredge  than  by  any  other  means,  a  brief  de- 
scription of  the  working  of  these  machines  is  here  given. 

There  are  two  general  types  of  dredges  used  for  this 
work,  differing  mainly  in  the  way  they  are  moved  over 
the  line  of  the  work.  One  is  the  float  dredge,  in  which 
the  machinery  is  mounted  on  a  float  boat,  the  engine 
in  the  rear  and  the  turn-table  and  excavating  machinery 
at  the  front.  The  excavator  is  in  the  form  of  a  large 
dipper  holding  from  \  yard  to  if  yards,  according 
to  the  size  of  the  machine,  and  is  operated  like  an 
ordinary  river  dredge.  The  dipper  is  lowered  to  the 
bottom  of  the  ditch  in  front  of  the  boat,  filled,  then 
raised  and  swung  to  one  side,  and  the  contents  dropped 
by  tripping  a  latch  which  allows  the  bottom  of  the  dip- 
per to  fall.  The  boat  is  prevented  from  tipping  over  on 
its  side  when  the  loaded  dipper  is  swung  by  strong 
braces  with  feet,  which  reach  to  the  bottom  or  rest  on 
the  bank  of  the  ditch.  As  the  excavation  proceeds, 
the  boat  is  made  to  float  forward  as  fast  as  desired. 
The  excavation  is  done  under  water,  the  depth  of  the 
ditch  being  gauged  mainly  by  the  height  of  the  water 
on  the  dipper  handle  as  it  descends  into  the  water  to 
be  loaded.  A  necessary  attendant  of  the  dredge  is 
the  floating  boarding-house  which  follows  a  few  hundred 
feet    in    the    rear.     This    is    fitted    up    with    kitchen, 


1/4  ENGINEERING   FOR    LAND   DRAINAGE. 

dining-roovn,  and  sleeping-berths  for  the  accommoda- 
tion of  the  working  force. 

Another  style  is  the  drag-boat  dredge,  which  be- 
gins operations  at  the  outlet  of  the  ditch  and  completes 
the  work  as  it  goes  up-stream.  The  excavating 
machinery  is  similar  to  that  just  described,  but  it  is 
mounted  compactly  on  a  boat  about  7  feet  deep,  the 
sides  having  an  angle  of  forty-five  degrees  and  a  bot- 
^m  as  wide  as  may  be  desired.  Some  are  made  as 
liarrow  as  4  feet  on  the  bottom.  The  machine  is 
moved  forward  by  means  of  a  wire  cable  which  is  an- 
chored a  few  hundred  feet  ahead  of  the  boat  and  at- 
tached to  a  winding  drum  placed  underneath  the  deck 
of  the  boat.  When  it  is  desired  to  move  the  boat  for- 
ivard,  the  drum  is  set  in  motion,  which  winds  up  the 
cable  and  moves  the  boat  forward.  Little  or  no  water 
is  required  for  the  successful  operation  of  a  machine  of 
this  kind.  The  ditch  can  be  dug  with  any  desired  side 
slope,  and  the  grade  can  be  followed  accurately  by 
means  of  guides  set  ahead  of  the  work  in  accordance 
Vvith  the  survey.  It  will  be  noticed  that  the  float 
dredge  must  have  water  to  work  in  and  begins  at  the 
upper  end  of  the  ditch  and  proceeds  down  the  stream. 
The  drag  boat  requires  no  water  except  to  supply  the 
boiler,  begins  at  the  outlet  and  propels  itself  up-stream. 
The  first  is'  adapted  to  large  ditches  where  the  water  is 
plenty.  The  second  is  used  most  successfully  for 
smaller  ditches,  where  the  water  supply  is  small  during 
the  operating  season. 

The  excavated  earth  is  dropped  on  either  side  of  the 
ditch,  leaving  a  clear  berm  of  from  6  to  8  feet  as  de- 
sired.     The  efificiency  of  these  machines  for  doing  this 


OPEN   DRAINS. 


175 


class  of  work  is  unquestioned.  By  means  of  them, 
large  and  deep  ditches  such  as  are  required  to  drain 
from  2000  to  40,000  acres  of  level  land  can  be  profitably 
excavated. 

The  machines  are  above  described  to  indicate  the  two 
general  methods  of  working  which  are  successfully 
used  rather  than  to  particularize  machines. 

Ditching  zuitJi    Teams. 

Ditching  with  teams  can  be  done  profitably  only 
under  favorable  conditions  of  earth  and  weather. 
Teams  can  be  worked  only  where  the  animals  can  ob- 
tain a  secure  footing.  The  excavation  is  done  with 
steel  scrapers  or  "slips"  after  the  earth  has  been 
loosened  with  the  plough.  Clay  that  contains  a  small 
per  cent  of  sand  will  cut  and  dump  with  ease,  while 
heavy  clays  of  all  kinds  are  exceedingly  tough  when 
found  in  their  natural  places  in  lands  requiring  ditches. 
However,  the  soil  and  subsoils  are  so  various  in  differ- 
ent localities  that  nothing  more  can  be  said  than  that 
where  this  method  is  used  every  advantage  of  soil, 
season,  and  weather  must  be  taken  or  the  work  may 
be  blocked  and  laid  over  until  the  next  favorable  time. 
Road-graders  with  carriers  for  depositing  the  earth 
clear  of  the  ditch-banks  may  be  used  where  the  earth 
will  plough  well  and  there  is  abundant  room  for  operat- 
ing. They  require  twelve  horses  and  three  men  and 
will  make  a  ditch  about  2  feet  deep  with  side  slopes 
of  2  to  I  or  more,  except  for  large  canals,  where  they 
can  be  used  to  advantage  for  any  depth  and  width. 

With  reference  to  laying  out  and  testing  ditches 
which  are  made  by  teams  it  should  be  observed  that 


1/6  ENGINEERING   FOR    LAND    DRAINAGE. 

every  survey  stake  near  the  line  of  work  will  .be  de- 
stroyed during  construction.  The  top  width  of  the 
ditch  should  be  laid  out  and  defined  by  the  stakes. 
The  first  work  of  the  contractor  should  be  to  mark  the 
outside  lines  of  the  ditch  by  a  well-defined  furrow,  and 
he  should  also  make  a  note  of  the  depth  of  the  pro- 
posed ditch  at  such  points  as  he  may  be  able  to 
identify..  The  ditch  should  be  inspected  and  tested  for 
grade  as  the  construction  proceeds.  To  do  this,  begin 
at  the  zero  or  beginning  point  of  the  ditch,  and  by 
measurement  reproduce  the  station  points,  take  levels 
at  these  points  on  the  bottom  of  the  ditch,  and  compare 
the  elevations  obtained  with  those  required.  It  will 
be  remembered  that  bench-marks  have  been  established 
at  convenient  intervals  along  the  line  for  the  purpose 
of  reference  during  construction,  and  no  ditch  should  be 
considered  finished  which  has  not  been  tested  in  this 
way. 

Discharge  of  Side  Ditches  into  Main. 

Much  trouble  is  experienced  in  alluvial  soils  or  those 
which  wash  easily  at  points  where  lateral  surface  water 
enters  the  main  ditch  by  reason  of  the  earth  which  is 
washed  into  the  main  and  is  frequently  found  deposited 
in  bars  at  or  near  the  junction.  This  is  particularly 
observed  at  points  where  a  large  main  ditch  crosses  a 
public  highway  and  the  water  from  the  shallow  road 
ditches  is  discharged  into  the  deeper  main  by  an  over- 
fall which  rapidly  cuts  away  the  earth  in  time  of 
freshet.  Much  of  this  difficulty  may  be  avoided  by  cut- 
ting the  lateral  ditches  down  to  such  a  grade  that  the 
point  of  discharge  will  be  near  the  bottom  of  the  main 


OPEN    DRAINS.  177 

as  shown  in  Fig.  32.  Provision  should  be  made  at  all 
points  where  water  discharges  into  open  ditches  in 
large  quantities  to  cut  off  the  overfall.  Much  injury 
to  ditches  and  after  expense  in  cleaning  out  may  in 
this  way  be  avoided.  The  line  AB  in  the  figure  shows 
how  the  grade  of  a  shallow  ditch  which  discharges  into 
a  deeper  one  should  be  changed  in  order  to  avoid  the 


Qrade  of  'BiWneh 


Fig.  32. — Section  showing  Junction  of  Shallow  Ditch  with  Deep  Main. 

erosion  of  earth  and  consequent  filling  of  the  receiving 
ditch  which  will  result  if  the  side  ditch  is  permitted  to 
discharge  on  its  regular  grade  by  an  overfall. 

Special  Forms  for  Ditches, 

In  practice,  ditches  are  not  made  in  the  same  form, 
but  are  adapted  to  the  material  through  which  they  are 
made,  the  means  used  for  their  excavation,  and  the 
office  they  are  to  perform. 

The  cuts  in  Fig.  33  show  forms  of  ditches  which  may 
be  found  in  use  and  serve  their  purposes  well.  Fig.  A 
is  the  common  form  left  by  the  floating  dredge  in  level 
districts  where  the  depth  is  from  6  to  8  feet.  j5  is  a 
form  used  for  a  deeper  ditch  where  clay  through  which 
it  is  cut  is  sufficiently  firm  to  stand.  (7  is  a  form  used  to 
provide  for  flood  water  from  hills.  For  ordinary  drain- 
age the  smaller  channel  is  sufficient.  This  is  adapted 
to  a  ditch  with  light  grade,  but  which  receives  water 
from  adjoining  territory  which  has  a  heavy  grade  and 


178 


ENGINEERING   FOR   LAND   DRAINAGE. 


which  requires  large  flood  capacity  for  a  short  time 
only. 

D  is  the  form  of  shallow  scraper  ditch  suitable  for 
surface  drainage  and  overflow  ditches.     They  may  be 


vmr  * 


Fig.  33. — Sections  of  Open  Ditches. 

mere  depressions  which  can  be  easily  crossed  with  teams 
or  may  be  moderately  deep  ditches  with  flat  sloping 
sides  which  can  be  cleared  of  grass  and  weeds  by  the 
use  of  the  mowing-machine. 

Such  a  form  of  ditch  should  be  selected  as  will  be 
suited  to  the  purpose,  taking  locality  and  work  to  be 
accomplished  into  account. 


CHAPTER   XII. 
DRAINAGE  OF   BARN- YARDS,  CATTLE-LANES,  ETC. 

The  stockman  is  familiar  with  the  difficulties  to  be 
met  in  keeping  ground  which  becomes  puddled  by  the 
frequent  tramping  of  live  stock  from  becoming  exces- 
sively muddy.  Such  ground  cannot  be  materially  ben- 
efited by  placing  tile  drains  underneath  the  puddled 
surface.  The  remedy  consists  in  preventing  all  water 
from  outside  sources  from  finding  its  way  to  the  yard, 
leaving  only  the  direct  rainfall  to  be  contended  with. 

The  roof  water  from  all  buildings  adjoining  the  yards 
should  be  taken  care  of  by  eaves-troughs,  and  down- 
spouts which  should  conduct  the  water  either  into  cis- 
terns or  into  a  tile  drain  provided  for  the  purpose. 
This  receiving  drain  should  be  laid  around  the  buildings 
and  discharge  into  some  open  channel  or  into  a  system 
of  field  drains.  A  tile  of  8 -inch  diameter  will  carry  the 
roof  water  from  a  large  barn,  and  may  discharge  into  a 
field  main  without  overcharging  it,  for  the  reason  that 
in  all  heavy  rainfalls  the  roof  water  will  have  passed 
through  the  drain  before  soil  water  will  have  had  time 
to  enter.  It  is  not  desirable  that  stock-yards  should 
be  kept  dry  by  surface  drainage  unless  the  value  of  the 
manure  is  to  be  disregarded.  It  is  the  practice  of  many 
good  farmers  to  so  arrange  the  stock-yards  that  all 
rainfall  will  gravitate  toward  the  center,  which  thereby 

179 


l80     ENGINEERING  FOR  LAND  DRAINAGE. 

becomes  the  receptacle  for  valuable  manures  and  gives 
drainage  to  the  outer  parts  of  the  yard.  In  all  cases 
the  surface  water  from  surrounding  land  should  be  cut 
off  by  shallow  trenches  supplemented  by  underdrains. 
These  suggestions,  if  followed,  will  result  in  a  great 
amelioration  of  the  mud  evil  so  often  endured  by  farm- 
ers and  stockmen  under  the  impression  that  there  is 
no  remedy  for  the  knee-deep  conditions  of  their  yards. 

Taking  Surface   Water  into  Underdrains, 

No  surface  water  should  be  permitted  to  enter  tile 
drains  direct  unless  precautions  are  taken  to  prevent 
mud  and  debris  from  entering  the  drain.  It  is  fre- 
quently desirable  to  remove  surface  water  by  means  of 
underdrains  from  certain  places  which  are  not  suscept- 
ible to  drainage  by  soil  filtration  nor  provided  with 
surface-drain  outlets.  Some  of  these  are  ponds  or  de- 
pressions by  the  roadside,  yards  which  are  kept  closely 
compacted  by  constant  use,  drainage  from  carriage 
washes  and  barns  which  is  charged  with  muddy  ma- 
terial, and  other  like  necessities. 

For  such  purposes  the  catch-basin  shown  in  Fig.  34 
will  serve  an  excellent  purpose.  It  is  a  well  con- 
structed with  brick,  3^  feet  in  diameter,  with  a  depth 
of  2  feet  below  the  outlet  pipe  for  the  settling  of  mud 
and  heavy  material  which  should  be  removed  when- 
ever the  space  below  the  discharge  is  filled.  The 
discharge  pipe  should  be  not  less  than  6  inches  in  di- 
ameter in  any  case  and  should  not  be  connected  with 
any  extensive  field  system,  but  should  extend  direct 
to  some  large  outlet.     The  inlet  should  be   10  or  12 


DRAINAGE    OF   BARN-YARDS,  ETC. 


I8l 


inches  in  diameter  and  have  two  rods  placed  vertically 
through  drilled  holes  near  the  entrance  to  serve  as  a 
screen.  Both  inlet  and  outlet  pipes  should  be  vitrified 
sewer-pipes  to  withstand  the  effects  of  freezing,  which 
common  clay  ware  will  not.  A  wooden  box  instead 
of  a  brick  well  will  serve  the  same  purpose,  but  must 


^mM 


J 


4^ 3ft.  6in.- » 


ii'iinmiiiMiiiiimiiiiiinuiiii- 


Fig.  34. — Catch-basin  for  Connecting  Surface  Drainage  with 

Underdrains. 

be  renewed  when  the  wood  decays,  and  is  obviously 
less  permanent  as  an  improvement.  In  some  respects, 
however,  the  wood  construction  is  more  desirable. 
The  inlet  may  then  be  a  hole  in  the  side  of  the  box  at 
the  surface  flow  line,  with  iron  rods  fastened  vertically 
across  it. 

A  serviceable  and  easily  constructed  catch-basin  may 
be  made  of  the  sections  of  24-inch  sewer-pipe,  which 
should  be  set  end  to  end  in  a  vertical  position  and  the 


l82 


ENGINEERING   FOR   LAND   DRAINAGE. 


socket  joints  secured  by  cement  mortar.  The  bottom 
section  should  be  a  straight  pipe,  the  upper  two  sec- 
tions should  have  T's,  one  of  which  should  be  used 
for  an  outlet  and  the  other  for  an  inlet.  A  2-inch 
plank  cover  fitted  and  dropped  into  the  top  socket  fin- 
nishes  a  neat  and  desirable  catch-basin.     See  Fig.  35. 


■^UUh 


Outlet  .^^ 


Fig.  35 — Catch-basin  constructed  of  Sewer-pipe. 

These  catch-basins  will  require  some  personal  at- 
tention at  times.  Straws  and  other  surface  rubbish  from 
the  surface  ditch  will  gather  against  the  inlet  and  must 
be  removed.  The  mud  which  accumulates  in  the.  bot- 
tom of  the  basin  should  be  removed  from  time  to  time. 
It  is,  however,  a  useful  and  convenient  accessory  to 
drainage  work. 


Drainage  of  Cellars  and  Residence  Grounds, 

Cellars  which  are  excavated  in  clay  or  loam  soils 
usually  become  wet  and  require  drainage.     A  common 


DRAINAGE   OF  BARN-YARDS,  ETC.  1 83 

method  of  procedure  is  to  construct  a  tile  drain  to  carry 
the  water  away  after  it  enters  the  cellar.  Another  is 
to  cover  the  walls  and  bottom  with  a  thick  coat  of 
cement  mortar  to  prevent  water  from  entering.  If 
there  is  much  soil  water  to  contend  with,  it  frequently 
bursts  through  the  coating  used  in  the  latter  method, 
and  when  the  former  is  used,  the  cellar  remains  damp 
even  when  the  drain  removes  the  free  water  which  per- 
colates through  the  soil  and  finds  its  way  to  the  low 
point  in  the  bottom  from  which  drainage  is  made. 

The  proper  plan  to  follow  is  to  prevent  water  from 
entering  by  means  of  a  tile  drain,  which  should  be  laid 
entirely  around  the  building  4  or  5  feet  distant  from 
the  walls  and  nearly  if  not  quite  as  deep  as  the  floor 
of  the  cellar.  This  drain  should  be  of  4-inch  tile  laid 
on  an  even  fall  of  i  inch  in  16  feet,  and  connect  with 
a  main  which  will  carry  the  drainage  safely  away 
from  the  house.  By  this  m.ethod  the  ground  about 
the  house  as  well  as  the  cellar  will  be  kept  dry  and 
wholesome,  and  is  the  best  known  plan  for  securing  a 
dry  cellar  for  a  country  house  where  natural  drainage 
is  deficient. 

The  underdrainage  of  the  ground  occupied  by  build- 
ings and  surrounding  yards  and  gardens  is  often  neg- 
lected on  the  supposition  that  these  grounds  have 
sufficient  natural  drainage,  which  is  not  always  the  case. 
The  filtration  of  all  surface  water  through  the  soil  of 
the  lawn,  garden,  and  surrounding  grounds  in  general, 
and  its  removal  by  the  process  of  underdrainage,  will 
add  much  to  the  ease  with  which  walks  may  be  con- 
structed and  maintained,  and  to  the  satisfactory  growth 
of  all  useful  and  ornamental  plants  which  contribute  so 


184  ENGINEERING  FOR  LAND  DRAINAGE. 

largely  to  the  beauty,  value  and  healthfulness  of  a  coun- 
try residence. 

The  water  supply  is  usually  taken  from  a  well  located 
near  the  residence.  While  the  supply  of  this  well  may 
have  its  source  in  a  vein  of  clay,  and  be  all  that  is  de- 
sired in  point  of  purity  and  coolness,  it  is  subject  to 
contamination  by  surface  and  soil  water  which  perco- 
lates through  the  earth  and  finds  lodgment  in  the 
well.  Some  deep  underdrains  laid  about  the  well  will 
prevent  the  pollution  of  the  water  from  this  source 
where  the  wells  are  located  on  level  or  undulating 
tracts  of  land. 

Drainage  of  Fruit  Orchards, 

Much  has  been  said  and  written  upon  the  subject  of 
growth  and  subsequent  fruitage  of  orchard  trees  in  vari- 
ous localities.  That  there  are  climatic  and  soil  con- 
ditions beyond  our  present  knowledge  which  have  a 
bearing  upon  this  industry  cannot  be  denied.  It  has 
been  observed  that  orchards  of  apple-trees  set  out  upon 
land  which  had  far  from  perfect  drainage  throve  and 
produced  excellent  fruit  for  a  series  of  years.  Later, 
trees  which  were  planted  on  an  adjoining  tract  under 
apparently  more  favorable  conditions  failed  to  make 
satisfactory  growth  or  to  produce  fruit  of  good  quality 
in  paying  quantities. 

There  are  examples  in  great  number,  however,  which 
show  the  value  of  underdraining  fruit  orchards  which 
are  located  upon  close  clay  soils,  or  others  which  are 
too  wet  for  the  growth  of  cereal  and  garden  crops. 
Fruit-trees  will  not  grow  well  on  wet  land.  The 
drains  shbuld  be  placed  midway  between  the  rows  of 


DRAINAGE   OF   BARN-YARDS,  ETC. 


185 


trees  and  extend  with  the  slope  of  the  land  to  an  in- 
tercepting main.  (Fig.  36.)  These  drains  should  be 
laid  4  feet  deep  if  possible.  It  will  be  found  that 
while  the  larger  part  of  the  roots  of  fruit-trees  are  in 
the  first  4  feet  of  soil,  there  are  roots  which  extend 
vertically  much  deeper  than  this  in  search  of  moisture 
when  it  is  lacking  nearer  the  surface.  No  stoppage 
of  drains  by  roots  of  fruit-trees  has  been  noted,  but  it 
should  be  observed  that  this  is  not  the  case  with  trees 


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Q, 
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feet 


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apart 


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Fig.  36.— Orchard  Drainage. 

like  the  willow,  water-elm,  and  others  which  are 
aquatic  or  water  trees  by  nature,  and  whose  roots  have 
been  known  to  seek  out  and  clog  tiles  where  growing 
30  or  more  feet  distant  from  the  drain.  Drains  which 
are  dry  during  a  large  part  of  the  year  are  rarely  found 
to  contain  roots  of  trees  of  any  variety,  while  those 
drains  which   have  a  constant  stream   of  water  ruj>- 


1 86  ENGINEERING   FOR   LAND   DRAINAGE. 

ning  through  them  attract  the  roots  of  aquatic  trees. 
The  tiles  should  be  laid  with  cement-covered  joints 
where  they  come  near  such  trees  or  the  trees  should 
be  destroyed.  The  experience  of  fruit-growers  along 
this  line  shows  that  the  decay  of  growing  trees  may 
often  be  arrested  by  deep  underdrainage.  An  eminent 
horticulturist  says  that  a  clay  soil  is  not  worth  the 
taxes  for  apple  culture  if  not  underdrained.  Every 
orchard  planted  on  clay  soil  should  have  an  underdrain 
between  the  rows  of  trees,  and  it  should  be  4  feet 
deep  if  possible.  Dr.  W.  I.  Chamberlain,  of  Ohio, 
in  commenting  on  the  drained  and  undrained  portions 
of  his  own  orchard,  says:  ''  I  have  now  nearly  finished 
picking  and  marketing  the  Red  Astrachans  on  a  row 
which,  like  all  the  other  varieties,  runs  across  both 
plats.  The  total  yield  per  tree  is  fully  50  per  cent 
greater  on  the  tiled  part,  and  in  size,  beauty,  and  even- 
ness of  shape  there  is  more  than  that  amount  in  favor 
of  the  tiled."  With  reference  to  the  growth  of  the 
trees  from  the  time  of  setting  to  maturity,  he  says  that 
on  the  untiled  land  he  lost  63  per  cent  of  those  planted, 
but  on  the  tiled  part  of  the  orchard  only  13  per  cent 
perished.  Those  interested  in  fruit  culture,  and  es- 
pecially those  contemplating  the  planting  of  large 
orchards,  should  look  into  this  subject  closely.  If  50 
per  cent  more  trees  can  be  brought  to  bearing  from 
the  first  planting  and  the  abundance  and  quality  of  the 
fruit  materially  increased  by  thorough  underdrainage, 
it  follows  that  both  new  and  old  orchards  on  clay  land 
or  black  soil  with  clay  subsoil  should  be  drained. 
These  are  facts  which  do  not  stand  alone,  but  can  be 
eir»phasized  by  similar  ones  in  other  localities. 


CHAPTER    XIII. 
ROAD  DRAINAGE. 

At  this  time  good  drainage  is  recognized  among 
road-builders  as  a  necessary  part  of  the  construction  of 
roads,  be  they  common  earth  roads  or  those  improved 
by  a  metal  covering.  Much  valuable  information  relat- 
ing to  the  construction  and  maintenance  of  public  roads 
has  been  collected  and  disseminated  by  the  Office  of 
Road  Inquiry  of  the  U.  S.  Department  of  Agriculture, 
and  the  bulletins  issued  from  that  office  form  a  valuable 
compendium  of  road  practice  in  this  country.  From 
these  it  is  not  difficult  to  learn  that  underdrainage  either 
natural  or  artificial,  as  well  as  surface  drainage,  is  held 
in  high  esteem  by  all  who  have  experience  in  construct- 
ing roads  over  good  agricultural  soils.  Drainage  has 
to  do  with  the  durability  and  maintenance  of  a  road 
after  it  is  once  constructed.  A  road  may  be  constructed 
without  proper  attention  to  foundation  and  drainage, 
and,  like  a  building  erected  under  similar  conditions, 
may  appear  well  at  first,  but  will  soon  show  weakness, 
with  threatening  dissolution. 

The  economical  and  successful  maintenance  of  a 
road  involves  the  following  principles: 

I.  The  travelled  surface  should  be  so  shaped  and 
of  such  hardness  that  all  storm  water  will  flow  ofif 
readily.     Could  the  earth   road   be  made  so  that  this 

187 


1 88  ENGINEERING  FOR  LAND  DRAINAGE. 

condition  would  be  secured,  the  question  of  how  to 
obtain  good  roads  in  the  country  would  be  answered. 
Soil  absorbs  water  easily,  so  that  it  is  scarcely  possible 
to  make  a  surface  that  will  shed  it  all,  especially  in 
climates  where  the  surface  is  subject  to  periodic  freez- 
ing, thawing,  and  rainfall.  Roads  which  are  excellent 
during  the  summer  season  when  the  road  surface  can 
be  kept  intact,  lose  all  semblance  to  their  summer  and 
fall  conditions  during  the  winter  and  spring  months, 
mainly  because  the  surface  is  not  water-proof. 

2.  Surface  ditches  at  each  side  should  be  provided 
and  so  graded  that  storm  water  from  the  road  surface 
will  be  removed  quickly. 

3.  In  order  that  the  travelled  surface  or  road  crust 
may  have  a  firm  foundation  at  all  seasons  of  the  year, 
underdrains  should  be  laid  on  one  or  both  sides  of  the 
road-bed  near  its  base,  to  prevent  the  saturation  of  the 
subsoil  beneath  the  road. 

These  three  elements  are  essential  to  every  good 
road  which  is  constructed  on  loam  or  clay  lands.  A 
thoroughly  drained  sub-grade  must  be  provided  if  we 
expect  to  maintain  a  good  surface,  whether  it  be  of 
earth  or  of  some  better  material.  The  difference  in  the 
practice  of  the  English  road-builders  Macadam  and 
Telford  gave  rise  to  sharp  discussions  regarding  the 
proper  foundation  for  stone  roads.  The  former  claimed 
that  the  base  should  be  formed  of  the  larger  size  of 
broken  stone  which  were  used  in  making  the  road 
covering,  while  the  latter  held  that  the  base  should  be 
formed  of  large  flat  stones,  upon  which  the  broken  stone 
should  be  placed.  With  thorough  sub-drainage  there 
is  no  cause  for  such  discussions.      It  is  only  where  such 


ROAD   DRAINAGE.  1 89 


f 

m':  drainage  cannot  be  obtained  that  a  base  of  large  stones 
or  timber  must  be  added  for  a  foundation  support. 
While  great  progress  has  been  made  in  the  improve- 
ment of  roads  in  many  localities  by  covering  with  some 
available  road  metal  such  as  stone,  gravel,  brick, 
and  slag,  the  improved  earth  road  is  the  base  of  all, 
and  of  necessity  must  be  the  road  used  by  the  mass  of 
people  in  country  districts ;  hence  the  principles  of  its 
construction  and  maintenance  should  be  familiar  to 
every  one. 

The  amount  of  travel  which  passes  over  a  road  has 
a  great  deal  to  do  with  the  completeness  with  which 
underdrainage  effects  it.  Where  roads  are  but  little 
travelled,  as  in  the  case  of  farm  roads  and  lanes  used 
by  a  neighborhood,  the  simple  drainage  of  land  by  one 
line  of  tile  lengthwise  through  low  places  has  proved 
sufficient  without  grading.  If  one  track  becomes  rut- 
ted, there  is  abundant  room  to  make  another  by  its 
side,  and  not  sufficient  travel  to  require  both.  Where 
the  travel  is  heavy,  as  it  is  over  all  leading  roads  to 
towns  and  railroad  stations,  the  case  is  entirely  differ- 
ent. When  the  entire  width  of  the  road  becomes  once 
cut  into  ruts,  and  in  wet  weather  puddled  on  the  sur- 
face by  the  continued  passage  of  loaded  teams,  no 
water  will  pass  through  the  soil  to  the  drains,  and 
without  an  embankment  and  side  ditches  the  road  will 
grow  worse.  The  underdrains  will  keep  a  good  base 
upon  which  to  build  a  road,  but  they  will  not  take 
water  from  a  puddled  surface.  On  all  such  roads  ex- 
perience has  proven  that  we  need  the  combined  action 
of  under  and  surface  drainage,  together  with  the  con- 
tinual oversight  and  care  of  the  travelled  surface.     One 


190  ENGINEERING   FOR   LAND   DRAINAGE. 

fact,  patent  to  every  observer  of  an  underdrained  road, 
is  enough  to  prove  the  necessity  of  surface  drainage, 
and  that  is  this :  That  when  by  any  means  a  rut  has 
been  made  and  puddled  by  the  continual  action  of  the 
wheels,  no  water  will  pass  through  the  soil  at  those 
places.  The  water  must  be  evaporated  or  the  puddle 
tapped  by  a  surface  ditch.  The  surface  of  a  road  must 
be  sufficiently  crowning  to  throw  off  all  water  possible, 
and  then  underdrains  at  the  side  will  prevent  the  bot- 
tom from  becoming  saturated  and  soft.  The  surface 
should  receive  such  care  at  times  as  is  necessary  to 
keep  it  crowning  and  to  drain  water  from  ruts  that  are 
sure  to  introduce  themselves  into  all  earth  road  sur- 
faces. A  line  of  tile  at  each  side  of  the  embankment 
gives  the  most  perfect  drainage.  Let  the  lines  be  so 
located  that  teams  cannot  drive  directly  over  them,  for 
their  value  for  taking  surface  water  depends  upon  some 
part  of  the  earth  near  the  drain  being  left  porous  and 
free  from  the  puddling  effects  of  passing  teams. 

Deep  side  trenches  are  not  desirable,  though  they 
may  serve  the  purpose  of  lowering  the  water  level  suffi- 
ciently for  road  purposes,  because  they  are  difficult  to 
keep  graded  so  that  the  water  will  all  flow  from  them, 
and  because  the  mowing-machine  cannot  be  con- 
veniently used  to  keep  the  grass  and  weeds  trimmed 
down,  which  is  also  a  desirable  part  of  road  main- 
tenance. Besides  this,  these  side  ditches  are  used  for 
a  winter  sleigh  road  in  latitudes  where  there  is  snow- 
fall, and  deep  ditches  are  usually  narrow  and  are  ill 
suited  for  such  use.  Broad  shallow  side  ditches  graded 
so  that  storm  water  may  flow  away  with  tile  drains  at 
the  inner  edge  to  remove  subsoil  water  form  the  best 


ROAD   DRAINAGE.  I9I 

known  plan  for  road  drainage.      This  method  of  drain- 
age is  shown  in  Fig.  37,  which  represents  a  road  surface 


Fig.  37. — Proper  Location  for  Surface  Ditches  and  Tile  Drains  in  Road 
Construction. 

18  feet  wide,  one  half  of  which  is  gravel  surface  and  the 
other  half  earth  surface.  This  is  regarded  as  the  most 
economical  method  of  road  improvement  at  low  cost 
now  in  use  where  a  hard  road  is  desired.  The  earth 
track  is  the  favorite  one  for  use  in  dry  weather  and 
for  light  loads,  while  the  gravel  track  is  used  for  heavy 
loads  and  at  times  when  the  dirt  track  is  wet.  In  this 
way  the  wear  is  shared  by  the  two  and  both  tracks 
easily  kept  in  order. 

Sub-drainage  has  lessened  the  cost  of  all  hard  roads 
by  demonstrating  that  a  less  thickness  of  road  covering 
or  road  metal  is  required  than  was  formerly  thought 
necessary.  All  experienced  road-builders  now  em- 
phasize the  importance  of  complete  underdrainage  in 
constructing  hard  roads.  With  a  firm  foundation 
which  underdrainage  secures,  it  is  only  necessary  to 
construct  and  maintain  a  good  wearing  surface.  With 
good  soil  drainage,  much  of  the  height  of  large  em- 
bankments may  be  reduced  by  lowering  the  line  of  sat- 
uration instead  of  raising  the  road  surface  by  costly 
earth  work  where  this  is  not  required  for  the  purpose 
of  obtaining  an  economical  grade. 


192 


ENGINEERING  FOR  LAND  DRAINAGE. 


Seepage   Water  on  Roads. 

It.  is  not  uncommon  to  encounter  water  veins  or 
"  spouty  ' '  places  where  excavation  for  road  grades  is 
made  in  grading  hills.  When  these  are  not  provided 
for,  they  present  one  of  the  most  serious  obstacles  to 
the  maintenance  of  the  road  surface.  The  remedy  for 
this  defect  may  in  most  cases  be  easily  and  effectively 
applied.     Find  where  the  water  comes  from  and  inter- 


FiG.  38. — Tile  Drain  to  Intercept  Seepage-water, 
cept  it  by  means  of  a  few  tile  drains  before  it  reaches 
the  base  of  the  road-bed.  Lay  the  drains  in  the  soil 
where  the  water  is  found  and  extend  the  outlet  line  to 
the  nearest  available  exit.  The  grade  of  the  lines  and 
workmanship  in  general  should  be  as  carefully  looked 
after  as  in  field  drainage.  Two  hundred  feet  of  3-inch 
or  4-inch  tile  wisely  used  will  frequently  abolish  a 
troublesome  mud-hole  on  a  hill  road. 

Surface  Drainage  of  Hill  Roads, 

Roads  on  hills  which  have  a  grade  of  3  per  cent  or 
more  are  frequently  injured  by  storm  water  making  a 
channel  in  the  middle,  or  in  the  wheel  tracks  of  the 


ROAD    DRAINAGE.  I93 

travelled  road,  which  soon  renders  it  unfit  for  use.  To 
prevent  this  the  surface  of  a  dirt  road  should  be  made 
crowning  as  much  as  ten  inches  in  a  20-foot  roadway. 
The  side  ditches  will  suffer  much  by  erosion  and  irreg- 
ular washing  unless  the  flow  is  controlled  by  occa- 
sional cutoffs  by  means  of  small  cross-culverts,  which 
will  divert  and  discharge  the  water  at  the  lower  side  of 
the  road  right-of-way  without  injury  to  either  road  or 
adjoining  land.  These  cross-drains  should  be  located 
at  favorable  points  along  the  grade,  and  should  consist 
of  good  sewer-pipe  not  less  than  10  inches  in  diameter 
laid  diagonally  across  the  road  track.  With  proper 
selection  of  the  location  and  the  adoption  of  the  plans 
suited  to  the  work,  the  top  of  the  culvert  may  be  placed 
18  inches  below  the  surface  of  the  road  and  will  con- 
stitute a  durable  improvement  worth  many  times  its 
cost.  The  joints  of  the  pipe  should  be  laid  in  good 
cement  mortar,  and  should,  if  possible,  have  a  grade 
of  I  foot  in  20.  These  cross-drains  being  laid  in  solid, 
not  filled  earth,  are  not  open  to  the  objection  urged 
against  pipe  culverts  which  are  laid  for  waterways  and 
covered  with  loose  embankment. 

Sewer-pipe,    Culverts,  and  Cross-drains, 

Experience  with  large  earthen  pipes  for  road  cul- 
verts has  demonstrated  that  they  frequently  fail,  not  by 
reason  of  lack  of  strength  to  resist  the  compression 
that  they  may  be  called  upon  to  bear,  but  because  of 
the  jar  or  vibration  which  is  communicated  to  them 
through  the  material  with  which  they  are  covered. 
These  failures  are  notable  in  locations  where  the  pipes 
are  bedded  in  and  covered  with  gravelly,  rocky,  or 


194  ENGINEERING   FOR   LAND   DRAINAGE. 

other  loose  material  which  does  not  become  thoroughly 
compacted.  When  a  load  pasess  over  them,  the  ma- 
terial conveys  a  vibration  to  the  covered  pipes  which 
subjects  them  to  a  series  of  shocks  which  in  time  shat- 
ters the  brittle  and  rigid  material  of  which  sewer-pipe 
is  composed.  When  the  pipes  are  full  of  frost  or  sur- 
rounded by  ice,  as  they  are  at  times  in  cold  climates, 
the  ware  is  especially  subject  to  fracture  by  shocks. 
That  this  is  the  cause  of  failure  rather  than  the  super- 
incumbent weight  or  compression  is  evidenced  by  the 
shattered  condition  of  the  sections,  whereas  if  they 
failed  by  pressure  the  breakage  would  be  in  cracks  par- 
allel to  the  length  of  each  piece.  The  double-strength 
sewer-pipe  has  given  but  little  better  results  than  the 
regular  thickness  for  the  obvious  reasons  already  noted. 
Railroad  companies  have  discarded  sewer-pipe  and  are 
substituting  cast-iron  pipe  for  small  culverts,  since  it 
was  found  that  the  tremor  of  embankments  caused  by 
passing  trains  destroyed  the  value  of  the  sewer-pipe 
culvert. 

Sewer-pipe  may,  however,  be  used  for  road  cross- 
drains  and  culverts  in  good  clay  soil  in  which  the  joints 
can  be  firmly  embedded  and  the  same  material  thor- 
oughly compacted  about  the  entire  length  and  with  the 
top  line  of  the  pipe  not  less  than  2  feet  below  the  sur- 
face of  the  road.  The  well-known  property  of  clay 
soil  to  form  a  bridge  or  crust  surface  under  continuous 
travel  does  much  to  carry  the  load,  while  the  elastic 
material  about  the  pipe  relieves  it  from  injurious  vi- 
brations. The  superiority  of  soil  or  sand  over  gravel, 
stone,  or  other  loose  material  for  bedding  or  covering 
culvert-pipe  has  been  proven  by  experience. 


ROAD   DRAINAGE.  I95 

In  laying  the  joints  of  pipe,  the  bell  end  should  be 
laid  up-grade,  the  spigot  end  fitted  into  the  bell  after 
the  bottom  of  the  latter  has  been  covered  with  cement 
mortar,  and  the  entire  joint  then  filled  with  the  same, 
making  a  continuous  and  water-tight  channel.  When 
the  joints  are  laid  dry,  water  frequently  runs  through 
them  in  sufficient  quantities  to  underwashthe  sections 
and  displace  them,  especially  if  the  fall  is  6  or  more 
inches  in  20  feet,  as  it  should  be  if  practicable.  A 
thorough  tamping  of  the  earth  about  the  pipe  is  indis- 
pensable to  a  good  culvert  of  this  kind. 

Drainage  of  Paved  Roads. 

The  construction  of  brick  and  macadam  roads  now 
in  use  in  Cuyahoga  County,  Ohio,  as  described  and 
illustrated  by  Mr.  J.  F.  Brown,  the  engineer,  in  Bulletin 
No.  17,  issued  by  the  Office  of  Road  Inquiry,  is  partic- 
ularly pertinent  and  suggestive  since  their  utility  has 
been  demonstrated  and  brought  into  favor  with  the 
travelling  public  of  that  progressive  county. 

He  says: 

*  *  A  description  of  the  building  of  the  road  known  as 
Wooster  pike  will  serve  to  illustrate  how  a  good  road 
may  be  made,  over  which  heavy  loads  may  pass  at  all 
times  of  the  year,  requiring  but  very  little  repairs  for  a 
long  term  of  years,  and  those  repairs  being  easily  and 
cheaply  accomplished. 

**  The  soil  along  that  road  is  a  heavy  white  clay,  hard 
to  drain  and  difficult  to  keep  in  place  unless  k  is  thor- 
oughly graded  and  prepared  to  resist  the  action  of  frost 
or  travel.  It  was  claimed  by  many  people  who  had 
spent  their  lives  in  the  neighborhood  that  it  would  be 


196  ENGINEERING  FOR   LAND   DRAINAGE. 

impossible  to  so  drain  a  road  in  that  kind  of  soil  that 
the  water  would  disappear  and  the  mud-holes  not  occur. 
I  think  now,  a  year  and  a  half  since  the  road  was  fin- 
ished, judging  from  the  heavy  travel  in  all  kinds  of 
weather,«  that  the  road  is  a  complete  success,  and  is  a 
practical  demonstration  that  a  clay  road  can  be  drained 
so  as  to  keep  a  uniform  surface  in  wet  weather.  The 
drainage  of  that  road  was  done  in  the  following  way: 

*  *  The  road  was  originally  60  feet  wide  from  fence  to 
fence.  We  graded  the  central  part,  making  a  roadway 
32  feet  wide.  On  each  side  of  the  roadway  was  made 
a  storm-ditch  of  an  average  depth  of  4  feet,  2  feet 
wide  on  the  bottom,  with  bank  slopes  of  i^  feet  hori- 
zontal to  I  foot  vertical.  After  the  road-bed  had  been 
brought  to  a  grade  line  and  thoroughly  finished,  a  line 
of  drain-pipe  6-inch  capacity  was  laid  along  each  side 
of  the  32  feet;  that  is  to  say,  a  trench  was  dug  16  feet 
from  the  center  line  of  the  street  to  a  depth  of  4  feet 
below  the  grade  line  of  the  road-bed.  The  trench 
after  laying  the  pipe  was  filled  with  stone  broken  to  a 
2j-inch  size.  The  pipe  used  was  a  second  quality 
of  vitrified  pipe,  which  can  be  procured  very  cheaply 
at  the  pipe  factory.  On  account  of  6-inch  pipe  being 
a  standard  size,  more  of  it  being  used  than  any  other, 
there  is  always  a  large  amount  of  what  are  called  "  sec- 
onds ' '  in  the  yard.  The  company  is  always  very  will- 
ing to  sell  them  very  cheaply,  and  they  answer  as  well 
for  drainage  purposes  as  first-class  pipe.  In  fact  they 
are  cheaper  than  the  soft  yellow  drain  tile,  which  are 
liable  to  break  and  stop  the  flow  of  water  in  the  pipe, 
causing  much  trouble  and  expense  for  repairs.  A  drain 
of  this  kind  was  laid  each  side  of  the  road-bed,  with 


ROAD    DRAINAGE.  I97 

outlets  for  water  at  every  cross-stream  or  ditch  where 
it  was  possible  to  discharge  the  water.  After  the  drains 
were  put  in,  a  strip  of  brick  pavement  was  laid  close 
to  one  of  the  drains,  leaving  24  feet  width  of  dirt  road 
for  summer  use.  This  dirt  was  repeatedly  rolled  with  a 
heavy  roller  until  the  upper  foot  or  2  feet  of  the  crust 
of  the  road-bed  became  hard  and  solid.     (See  Fig.  39.) 


20  ft. 


Storm  Water  '  ^'''^^ 


4|^t*Trench  filled  with  Broken  Stone 
^^'Tile  Drain. 

Fig.  39. — Combined  Brick  and  Clay  Road  as  constructed  in 
Cuyahoga  Co.,  Ohio. 

Our  work  on  that  road  has  demonstrated  that  heavy  roll- 
ing of  a  road  which  has  been  properly  drained  will  form 
a  crust  or  roof,  so  that  water  cannot  stay  on  the  road, 
but  must  flow  at  once  into  the  drain-pipe  and  disappear; 
and  in  case  of  storm  water  too  rapid  for  the  pipe-trench 
to  catch  and  carry  off,  the  water  flowed  over  the  pipe- 
trench  into  the  storm-ditches,  which  never  fail  to  carry 
off  all  the  water  that  comes.  Since  the  road  was  fin- 
ished there  has  been  no  break,  no  settlement,  no  stop- 
page of  water,  no  ruts,  no  mud,  and  travel  on  the  road 
has  doubled  many  times,  thus  showing  the  popularity 
of  a  hard,  even  roadway  for  winter  travel  as  well  as 
summer. 

* '  The  method  of  holding  the  brick  in  place  alongside 
of  the  dirt  road  was  devised  by  me,  and  consists  of  three 
courses  of  brick  standing  endwise,  the  first  course  flush 
with  the  top  of  the  pavement,  the  second  breaking 
joints  and  dropping  2  inches  lower,  and  the  third  2 


198  ENGINEERING   FOR    LAND   DRAINAGE. 

inches  lower  still ,  forming  a  stairwise  bond  for  the  brick- 
work in  such  a  manner  that  a  heavily  loaded  wagon 
cannot  catch  and  tear  up  the  brick  pavement.  If  a 
wheel  runs  off  the  pavement  it  strikes  the  second  course 
of  curbing  brick  and  runs  along  on  that;  but  it  is 
almost  impossible  for  a  wheel  to  cut  through  the  broken 
stone  filling  which  surrounds  the  curbing  courses  and 
protects  them  from  the  wear  of  heavily  loaded  wagons. ' ' 


CHAPTER   XIV. 
DRAINAGE  DISTRICTS. 

A  DRAINAGE  district  is  an  organization  of  the  owners 
of  land  for  the  purpose  of  constructing-  and  maintaining 
adequate  drainage  outlets  for  individual  use  in  which 
the  expense  of  the  work  is  shared  by  each  in  proportion 
to  the  benefits  derived. 

The  boundary  of  a  district  should  in  all  cases,  if  pos- 
sible, include  an  entire  water-shed,  so  that  when  an 
outlet  is  secured  and  drainage  provided  for,  it  will  be 
complete  in  itself  as  respects  its  drainage.  The  forma- 
tion and  management  of  districts  is  provided  for  in 
many  States  by  laws  which  direct  in  detail  the  steps 
which  should  be  taken,  and  give  methods  of  procedure 
which  must  be  followed  closely  in  order  to  make  the 
proceedings  legal. 

The  principles  now  fairly  well  recognized  in  the 
execution  of  all  public  land  drainage  where  individual 
property  is  affected  and  which  must  bear  the  expense 
of  the  improvement  may  be  stated  as  follows : 

The  plan  for  the  work  should  be  complete  and  pro- 
vide each  landowner  an  adequate  outlet  which  he 
may  use  without  being  accountable  to  neighboring 
property.  Each  property  should  be  assessed  for  the 
first  cost  and  subsequent  maintenance  of  the  work  in 
proportion  to  the  benefit  it  will  derive  from  the  same, 

199 


200  ENGINEERING   FOR   LAND   DRAINAGE. 

taking-  into  account  the  drainage  advantages  which  each 
property  possesses  by  nature. 

The  work  should  be  undertaken  only  after  it  has  been 
shown  that  the  benefits  which  will  accrue  to  the  prop- 
erties concerned  will  be  greater  than  the  expense  of 
the  improvement,  and  should  be  executed  with  due 
regard  to  economy  and  permanency. 

Plans. 

The  natural  boundary  of  the  area  should  be  deter- 
mined with  accuracy.  Where  the  drainage  divide  is 
not  apparent  from  observation,  levels  should  be  taken 
to  determine  the  dividing-  line  between  water-sheds,  for 
upon  this  point  will  often  depend  the  legality  of  assess- 
ments upon  certain  tracts  for  the  cost.  There  are  table- 
lands or  levels  where  there  is  no  little  difficulty  in 
determining  the  natural  divide.  In  fact  some  tracts 
may  be  drained  by  artificial  methods  as  easily  in  one 
direction  as  in  another,  but  the  natural  drainage  of  a 
tract  as  held  by  the  courts  is  the  direction  in  which 
the  water  will  flow  when  the  entire  surface  of  the  land 
becomes  covered  with  water.  The  belt  of  land  which 
first  becomes  dry  when  drainage  takes  place  under 
such  conditions  is  the  natural  divide,  and  should  be 
regarded  as  the  boundary  line  of  the  area  to  be  in- 
cluded in  a  district.  A  map  should  be  made  showing 
the  acreage  and  ownership  of  each  farm,  and  upon  this 
the  boundary  line  of  the  district  should  be  distinctly 
marked.  The  natural  outlet  for  the  district  may  be 
obvious,  but  its  size  insufficient,  in  which  case  it  should 
be  improved.     The  size  and  best  dimensions  for  the 


DRAINAGE   DISTRICTS.  201 

work  should  be  determined  by  the  methods  outlined  in 
previous  chapters.  The  topography  should  be  found 
in  detail  sufficiently  to  furnish  data  for  the  necessary 
computations  for  defining  the  dimensions  that  will  be 
required  for  the  main  outlet  and  for  such  branches  as 
may  be  needed  to  provide  for  the  drainage  of  individual 
lands.  The  provision  of  outlets  for  the  property  of 
owners  located  at  some  distance  from  the  main  channel 
or  drain  will  incidentally  require  the  construction  of 
drains  across  farms  which  will  thereby  be  much  more 
completely  drained  at  the  general  expense  than  other 
tracts  for  which  a  mere  outlet  is  constructed  to  the 
property  line.  In  such  cases  there  is  a  difference  in 
the  amount  of  benefit  conferred  by  the  work  which 
must  be  considered  in  apportioning  the  cost  to  the  sev- 
eral owners. 

The  system  may  consist  of  open  ditches  supple- 
mented by  large  tile  drains,  or  of  either  separately,  ac- 
cording to  the  area  to  be  drained  and  the  requirements 
of  the  land  which  will  be  affected.  Where  it  is  desira- 
ble to  use  large  tiles  for  mains,  and  to  lay  them  in  the 
line  of  natural  drainage  courses,  it  is  always  wise  to 
provide  overflow  ditches  which  will  relieve  the  surface 
at  times  of  unusually  heavy  rainfall  and  at  the  same 
time  retain  the  benefits  which  are  peculiar  to  under- 
drains.  (Fig.  40. )  These  surface  drains  should  be  shal- 
low and  broad  and  so  graded  that  while  all  water  may 
be  removed  from  the  surface  by  the  open  ditch,  the 
flood  water  will  pass  off  in  sufficient  quantities  to  per- 
mit the  tile  drain  to  complete  the  work  perfectly.  The 
surface  drains  may  be  called  into  action  only  occasion- 
ally, but  at  certain  times  save  crops  worth  many  times 


202  ENGINEERING   FOR   LAND   DRAINAGE. 

the  cost  and  care  of  such  drains.  Experience  has 
demonstrated  that  in  well-watered  sections  tile  drains 
which  are  intended  to  provide  outlets  for  large  tracts 
cannot  be  made  large  enough  without  too  great  ex- 
pense to  take  care  of  exceptionally  heavy  rainfall  with- 


FlG.  40.— Tile  Drain  with  Relief  Surface  Ditch. 

out  the  aid  of  surface  drains.  Another  reason  for  the 
necessity  of  this  provision  is  that  many  soils  which 
under  ordinary  conditions  will  respond  readily  to  the 
action  of  tile  drains  in  removing  water  from  the  surface 
through  the  soil  will  not  permit  a  sufficiently  large 
quantity  of  water  to  pass  to  the  drains  in  the  short  time 
required.  If  the  ditches  are  left  broad  and  shallow  they 
will  cause  but  little  inconvenience  and  may  be  utilized 
for  cultivated  field  crops  or  for  grass. 

An  estimate  of  the  cost  of  the  entire  proposed  work, 
including  construction,  legal  and  administration  ex- 
pense, should  be  made  and  apportioned  to  the  several 
property  owners  and  interests  concerned  in  the  work. 

The  Theory  of  Classification  of  Lands. 

The  first  step  to  be  taken  in  determining  the  appor- 
tionment of  cost  which  each  tract  of  land  should  bear 
is  to  fix  upon  some  scale  of  marking  which  shall 
numerically  express  the  benefits  to  each  tract  of  land, 
and  which  may  be  used  in  making  a  just  and  equitable 


DRAINAGE   DISTRICTS.  203 

distribution  of  the  entire  expense  connected  with  the 
construction  and  maintenance  of  the  projected  work. 

This  is  one  of  the  most  delicate  matters  involved  in 
cooperative  drainage,  since  there  are  many  different 
opinions  among  landowners  and  others  concerning  the 
proper  distribution  of  cost,  the  judgment  of  some 
interested  parties  being  frequently  biased  by  personal 
considerations.  It  may  be  asserted  with  truth  that  the 
classification  of  land  for  this  purpose,  even  when  made 
with  the  utmost  care  and  good  judgment,  will  be  open 
to  just  criticism  from  some  point  of  view. 

Each  of  the  following  principles  should  have  a  value 
in  the  classification  of  land  in  a  drainage  district: 

Each  landowner  is  entitled  to  such  natural  drainage 
as  his  land  possesses  by  right  of  ownership.  If  his 
land  is  so  situated  that  he  can  thoroughly  drain  it  into 
channels  provided  by  nature  without  crossing  his  neigh- 
bor's land  in  the  construction  of  drains  he  should  not 
be  required  to  assist  in  carrying  out  a  plan  of  coopera- 
tive drainage,  except  on  the  ground  that  the  proposed 
work  will  promote  the  public  health  or  enhance  the 
general  value  of  property  in  the  community. 

Each  landowner  may  drain  his  land  as  he  chooses 
provided  he  does  it  within  the  boundary  of  his  own 
possessions,  into  an  outlet  channel  provided  by  nature. 

A  tract  of  land  which  is  wet  and  practically  useless  for 
agricultural  purposes  should  be  assessed  proportionally 
higher  if  reclaimed  by  the  drainage  system  than  that 
which  has  better  natural  drainage. 

A  tract  which  lies  distant  from  a  natural  outlet  should 
be  taxed  higher  than  one  lying  near,  provided  both 
receive  the  same  drainage  advantages.      This  obtains 


204  ENGINEERING   FOR   LAND   DRAINAGE. 

on  the  theory  that  a  tract  near  natural  drainage  in  a 
state  of  nature  bears  a  higher  value  by  reason  of  this 
fact  than  one  which  is  distant  and  whose  lack  of  nat- 
ural drainage  is  recognized  as  a  cause  of  diminished 
value. 

In  case  a  public  drain  passes  through  a  farm  for  the 
purpose  of  giving  drainage  privileges  to  another  farm, 
and  in  so  doing  incidentally  diminishes  the  individual 
expense  which  will  be  Required  to  complete  the  detail 
drainage  of  the  first  farm,  it,  the  first  farm,  should  be 
assessed  higher  proportionally  than  the  second,  on  the 
theory  that  private  drainage  has  been  done  on  the  first 
farm  at  general  expense. 

Classification  for  Assessment  Purposes, 

A  classification  map  should  be  prepared  which  shows 
the  name  of  the  owner  of  each  separate  piece  of  land, 
the  location  and  the  kind  of  drains  proposed  and  the 
estimated  cost  of  each  of  the  mains,  and  the  total  esti- 
mated cost. 

With  this  map  in  hand,  the  party  or  parties  to  whom 
is  intrusted  the  classification  from  which  the  assessment 
roll  is  to  be  prepared  should  make  a  personal  exam- 
ination of  each  tract  or  farm  included  in  the  district, 
noting  carefully  the  natural  condition  and  location  of 
the  land  and  the  comparative  benefit  which  each  tract 
will  receive  from  the  proposed  work.  Use  the  number 
100  to  represent  the  classification  of  the  tract,  be  it  large 
or  small,  which  will  receive  the  greatest  benefit  consid- 
ering the  principles  which  have  been  heretofore  stated. 
Compare  other  tracts  with  this  and  rate  each  on  the 
per  cent  system,  40-60-70,  etc.,  placing  the  classifica- 


DRAINAGE   DISTRICTS.  205 

tion  number  upon  the  respective  tracts.  This  classifi- 
cation may  be  reviewed  and  amended  until  it  is  agreed 
that  these  numbers  represent  the  proper  ratios  of  bene- 
fit which  the  several  tracts  or  farms  will  receive  by 
reason  of  the  construction  of  the  drainage  system. 

In  case  the  public  highways,  the  township  or  county 
are  benefited  as  organizations,  and  are  legally  subject 
to  assessment  for  the  same,  they  cannot  be  classified 
upon  the  same  basis  as  agricultural  lands,  but  a  certain 
per  cent  of  the  entire  cost  should  be  charged  up  to  each 
and  deducted  from  the  sum  total,  after  which  the  re- 
mainder should  be  spread  over  the  district  as  per  classi- 
fication. 

All  of  this  work  is  a  matter  of  judgment,  and  upon 
it  will  depend  the  equitable  and  proper  distribution  of 
the  cost.  It  cannot  be  done^  too  carefully,  and  should 
be  several  times  reviewed  before  it  is  finally  approved. 

To  find  the  part  of  the  total  cost  that  each  owner 
should  pay,  proceed  as  follows: 

1.  Deduct  from  the  total  estimated  cost  of  the  work 
the  several  amounts  assessed  against  highways,  town- 
ships, corporations,  etc.,  to  obtain  the  amount  that 
is  to  be  charged  to  the  classified  lands. 

2.  Multiply  the  number  of  acres  in  each  tract  by  its 
classification  mark. 

3.  Find  the  sum  of  these  several  products. 

4.  Divide  the  amount  to  be  apportioned  to  the  sev- 
eral tracts  by  the  sum  of  the  several  products  and  mul- 
tiply each  product  by  this  quotient  to  obtain  the  amount 
that  should  be  assessed  against  each  tract  as  shown 
upon  the  roll.  These  several  amounts  when  added  to- 
gether should  equal  the  total  estimated  cost. 


2o6 


ENGINEERING   FOR  LAND    DRAINAGE. 


The    assessment   roll    and    classification    map   here 
given  (Fig.  41)  will  serve  to  illustrate    the    methods 


Fig.  41. — Classification  Map  of  a  District  containing  3525  Acres. 
(Classification  figures  in  parenthesis.) 


described  and  in  a  measure  the  principles  of  land  clas- 
sification for  district  purposes.  In  addition  to  the  col- 
umns shown  in  the  roll  here  given  the  description  as  to 
section,  etc.,  of  each  owner's  land  should  immediately 
follow  the  name. 

There  are  always  many  questions  peculiar  to  each 
case  coming  up  in  this  kind  of  drainage  work  which 
must  be  met  and  disposed  of  in  the  wisest  manner  pos- 
sible. The  men  who  have  charge  of  the  work  as  com- 
missioners should  be  conversant  with  land-drainage 
matters  in  general,  and  with  the  proposed  work  in  par- 
ticular, in  order  to  be  able  to  exercise  good  judgment 


DRAINAGE    DISTRICTS. 


207 


regarding  the  effect  that  the  execution  of  the  contem- 
plated work  will  have,  and  be  ready  to  give  proper 
consideration  to  suggestions  and  opinions  which  may- 
be advanced  by  interested  landowners. 


ASSESSMENT  ROLL  O?  CRESCO  DRAINAGE  DISTRICT. 

Total  estimated  cost $6280 . 00 

Amount  assessed  against  township  highways 628.00 

Balance  to  be  assessed  against  farm  lands $5652 .  00 


Names  of  Owners. 


Acres. 


Classifi- 
cation. 


Product. 


Assess- 
ment. 


J.  Brown.  .  . 
S.  Webber  . 
Rufus  Clay  . 
C.  Cross. .  .  . 
Silas  Huff  . . 
J.  Snider  ... 
G.  Fender  . . 
R  Clifford  . 
J.  Robbins.. 

E.  Philo  .  .  . 
R.  Stump  .  . 
R.  Humel  .. 

J.  Ott 

C.  Ott 

F.  Omo 

J.  Moon.  .  .  . 

R.  Sill 

S.  Sutton  . . 

F.  Foss 

N.  Hanson.. 
K.  Humes.  . 
R.  Huss  .  .  . 
F.  Hummer 

J.  Utt 

C.  Nelson  . . 
S.  Johns  .  .  . 
C.  Clements 
N.  King  .  .  . 

F.  Root 

E.  James.  .  , 


Public  highways 


160 

90 

160 

120 

130 

120 

160 

160 

160 

80 

160 

180 

100 

80 

60 

115 

so 

SO 

80 

80 

80 

120 

120 

40 

160 

80 

170 

80 

160 

220 


45 
50 
SO 
40 
50 
55 
60 
60 
60 
85 
80 
85 
100 
100 
90 
90 
90 
95 
100 
100 
100 
70 
60 
20 
65 
60 
70 
70 
80 
70 


7,200 
4,500 
8,000 
4,800 

(ij-^OO 

6,600 

9,600 

9  600 

9,600 

6,800 

12,800 

15,300 

10,000 

8,000 

5. 400 

10,350 

4,500 

4,750 

8,000 

8,000 

8,000 

8,400 

7,200 

800 

10,400 

4,800 

11,900 

5,600 

12,800 

15,400 


245,600 


$165.70 
103-57 
184. 10 
110.46 
I49S9 
151.89 
220.93 
220.93 
220.93 
156.48 
294.56 
352.09 
230.13 
184. 10 
124.27 
238.18 
103.56 
109.31 
184. 10 
184. 10 
184. 10 
193.32 
165.70 
18.42 
239.33 
110.47 
273.85 
128.88 
294.56 
354.39 


$6280.00 


5652 

=    .02301. 

245,600 

Note. — The  column  headed  "Product"  gives  an  equivalent  number  of 
acres  classified  at  i  per  cent. 

The  number  .02301  represents  the  amount  of  assessment  on  one  acre  clas- 
sified at  I  per  cent. 


208  ENGINEERING   FOR   LAND    DRAINAGE. 


Mutual  Cooperative  Drainage. 

The  same  principles  of  work  may  be  applied  to  small 
drainage  schemes  as  those  which  are  employed  in 
drainage  districts  in  which  it  is  not  necessary  to  work 
under  legal  restrictions.  In  other  words,  it  may  be  a 
partnership  plan,  mutually  arranged  and  agreed  upon, 
from  which  will  result  the  same  advantages  without  in- 
curring the  delay  and  expense  involved  in  operating 
under  the  statute. 

A  plan,  estimate,  and  assessment  may  be  submitted 
by  the  engineer,  made  out  by  drainage-district  methods 
and  submitted  to  the  parties  concerned  for  their  con- 
currence. If  it  is  acceded  to,  nothing  stands  in  the 
way  of  entering  into  an  agreement  and  executing  the 
work  according  to  the  accepted  plans,  in  which  case 
the  necessary  expenses  will  be  reduced  to  a  minimum. 
This  is  a  commendable  method  when  interested  parties 
can  agree. 


CHAPTER   XV. 
ESTIMATES  OF  COST. 

An  estimate  of  the  cost  of  a  proposed  drainage  work 
is  expected  of  the  engineer,  and  is  important  before  the 
execution  of  the  work  begins.  In  the  case  of  the  drain- 
age of  a  field  or  farm,  a  preliminary  estimate  may  be 
made  from  an  inspection  of  the  land  based  upon  a 
knowledge  of  what  the  drainage  of  other  tracts  of  land 
similar  in  requirements  has  cost.  No  correct  estimate 
can  be  made,  however,  until  the  lines  have  been  lo- 
cated and  measured  and  the  sizes  of  tile  to  be  used 
decided  upon. 

The  cost  of  material  and  labor  in  the  locality  where 
the  work  is  to  be  done  must  be  ascertained  and  tabu- 
lated. The  following  is  a  schedule  of  the  items  that 
should  be  considered  in  estimates  for  farm  drainage: 

1.  Total  number  of  each  size  of  tile  required. 

2.  Cost  of  tile  at  factory. 

3.  Cost  of  freight  to  nearest  railroad  station,  if 
shipped. 

4.  Hauling  from  factory  or  station  and  distributing 
on  the  drain  lines. 

5.  Digging  ditches  and  laying  tile. 

6.  Filling  ditches. 

7.  Laying  out  and  superintending. 

209 


2IO 


ENGINEERING   FOR    LAND   DRAINAGE. 


Schedule  for  Making  Estimates. 

The  following  schedule,  subject  to  amendment  as 
prices  vary,  may  be  used  in  making  estimates.  The 
weight  of  the  individual  tiles  varies  somewhat  with  dif- 
ferent factories,  as  does  also  the  length  and  diameter. 
The  joints  from  some  factories  are  \2\  inches  long, 
while  from  others  they  are  even  12  inches.  The 
prices  here  listed  are,  at  this  date  (1902),  considered 
fair  average  prices  at  the  factory.  The  joints  of  tile 
12  inches  in  diameter  and  above  should  be  2  feet  long 
for  convenience  in  handling  and  for  strength. 

PRICES  AND  WEIGHTS  OF  DRAIN-TILES. 
(Note. — Prices  vary  in  different  localities.) 


Size  in  Inches. 


Price  per 
1000  Feet. 


$10.00 

iS-oo 

2 1. 00 

27.00 

36.00 

45- 00 

54. 00 

60.00 

90.00 

135-00 

150.00 

165.00 

240.00 


Weight  per 
Foot. 
Lbs. 


4i 
6i 
9 

Hi 

14 


Average 

Car  Load. 

Feet.* 


6000 

4000 

3000 

2200 

2000 

1250 

1000 

850 

750 

600 

500 

450 

350 


*  If  large  and  small  sizes  are  loaded  in  the  same  car,  the  freight  cost  will 
be  lessened  on  a  field  list  of  tile. 


Hauling  and  distributing  tile  can  be  figured  by  the 
cost  per  ton,  using  as  a  basis  the  number  of  loads 
which  can  be  hauled  per  day,  when  the  road  is  good, 
by  one  man  and  team. 

With  wages  of  team  and  driver  at  $3.00  per  day, 
two  men,  each  with  a  team,  working  together  so  that 


ESTIMATES    OF   COST.  211 

one  can  assist  the  other  in  loading  and  unloading,  haul- 
ing and  distributing  tile  will  cost  approximately  as 
follows : 

Hauling  one  mile $0-55  per  ton 

**       two  miles 70    '*      ** 

**       three  miles.  .  .  .     i.oo    **      *' 

**       four  miles 1.25    **      ** 

**       five  miles 1.40    ♦*      '* 

The  tile  should  be  strung  along  the  lines  staked  out 
for  work  if  it  is  to  be  done  soon ;  if  not,  they  should  be 
placed  in  neat  piles  of  25  each,  at  regular  intervals  of 
25  feet,  near  the  line  of  each  drain.  A  sketch  or  dia- 
gram of  the  location  and  sizes  should  be  given  to  the 
one  in  charge  of  the  distribution  so  that  this  part  of  the 
work  may  be  done  correctly. 

The  difficulties  to  be  encountered,  such  as  the  con- 
dition of  the  roads,  the  fields,  and  inconveniences  of 
loading  and  unloading,  must  be  taken  into  account, 
which  will  often  materially  change  the  foregoing  fig- 
ures that  should  be  used  in  estimating  the  cost  of  the 
delivery  of  tile  upon  the  ground. 

Digging  the  ditches  and  laying  the  tile  are  so  fre- 
quently contracted  for  and  done  by  the  rod  or  100  feet, 
that  a  price  is  pretty  well  established  for  drains  in  soils 
which  are  easily  worked  with  the  spade  and  shovel,  and 
which  is  here  stated  as  a  basis  upon  which  to  work. 

Where  the  land  is  stony,  filled  with  roots  or  is  so 
hard  that  it  must  be  picked  or  loosened  with  mattocks, 
the  cost  will  be  much  increased  and  must  be  figured 
with  a  liberal  margin  in  order  to  cover  unforeseen 
contingencies. 


212 


ENGINEERING   FOR   LAND   DRAINAGE. 


COST  OP  DIGGING  DITCH  AND   LAYING  TILE  TO  GRADE. 

3''  to  &'  tile       2  to  3  ft.  deep,  $i.20  per  lOO  ft. 


( (       ( (     ( t 

( < 

3 

to  4  '^       '' 

1.50 

( (        t  (      ( ( 

<  ( 

4 

to  5  '*      *' 

2.10 

f'  and  S'' 

tile 

3 

to  4  '*      " 

1.80 

li      {(      it 

<  < 

4i  ''      *' 

2.40 

<  (      ( (      ( ( 

<  ( 

5  ^'      '' 

3.50 

g"  to  12'' 

i( 

4  -      - 

3.00 

t  <    ( <    <  ( 

<< 

5  ''      '' 

3.60 

Filling  the  ditches  in  cultivated  land  can  be  done 
with  a  team  and  plough  for  10  cents  per  100  feet.  In 
meadows  where  care  must  be  taken  to  leave  the  sur- 
face uninjured,  for  15  cents  per  100  feet.  Where  the 
filling  must  all  be  done  by  hand  work  it  will  cost  about 
25  cents  per  100  feet. 

Laying  out  and  superintending  are  worth  about  5  per 
cent  of  the  total  estimated  cost  where  nothing  is  re- 
quired but  location  and  levelling  lines  and  final  inspec- 
tion of  the  drains  before  they  are  covered. 


TABLE  SHOWING  THE  NUMBER  OF  CUBIC    YARDS  OP  EARTH  IN 
ONE  ROD  OF  DITCH  OP  VARIOUS  DIMENSIONS. 

{Excavation  for  Tile  Drains.) 


il 

Mean  Width. 

aS. 

7  In. 

8  In. 

9  In. 

10  In. 

11  In. 

12  In. 

13  In. 

14  In. 

IS  In. 

16  In. 

17  In. 

18  In. 

30 

0.89 

1 .02 

i.iS 

1.27 

1.40 

1.53 

1.6s 

1.78 

1. 91 

2.04 

2.16 

2.29 

33 

0.98 

1. 12 

1.26 

1.40 

1.54 

1.68 

1.82 

1.94 

2.10 

2.24 

2.38 

2.52 

36 

1.07 

1 .  22 

1.38 

1.53 

1.68 

1.83 

1.98 

2.14 

2.29 

2.24 

2.60 

2.75 

JJ 

1. 16 

1.32 

1.49 

1. 6s 

1.82 

1.98 

2.15 

2.32 

2.48 

2.6s 

2.8l 

2,98 

42 

1.25 

1.42 

1.60 

1.78 

1.96 

2.14 

2.32 

2.49 

2.67 

2.8s 

3.03 

3.21 

45 

1.34 

I. S3 

1.72 

1.91 

2.10 

2.29 

2.48 

2.67 

2.86 

3.05 

3.24 

3.44 

48 

1.43 

1.63 

1.83 

2,04 

2.24 

2.44 

2.65 

2.85 

3 -OS 

3.26 

3.46 

3.67 

SI 

1.52 

1.73 

1.95 

2.16 

2.38 

2.60 

2.81 

3.03 

3.25 

3.46 

3.68 

3.90 

54 

1 .60 

1.83 

2.06 

2.29 

2. 52 

2.75 

2.98 

3.20 

3.44 

3.66 

3.89 

4.12 

57 

1.69 

1.94 

2.18 

2.42 

2.66 

2,90 

3.14 

3.38 

3.63 

3.87 

4. II 

4.3s 

60 

1.78 

2.04 

2.29 

2.54 

2.80 

3. OS 

3.31 

3.56 

3.82 

4.07 

4.33 

4.58 

ESTIMATES   OF  COST.  213 

Total  Estimate. 

By  going  over  the  foregoing  items  in  detail  and 
adapting  the  prices  to  the  locality,  a  correct  estimate 
may  be  summed  up  for  the  cost  of  the  work  on  the  en- 
tire field,  farm,  or  tract,  which  should  be  charged  to 
the  number  of  acres  which  wiU'be  benefited  by  the  pro- 
posed improvement. 

From  what  has  been  said  in  previous  chapters  upon 
the  frequency  and  depth  of  drains,  it  is  readily  seen 
that  there  will  be  a  wide  difference  in  the  cost  of  work 
according  to  locality  and  kind  of  soil  operated  upon. 
The  cost  per  acre  for  the  entire  tract  improved,  rather 
than  the  cost  of  individual  drains,  should  be  sought. 

Profit  on  the  Investment. 

How  much  will  the  land  be  benefited  }  How  much 
will  the  production  be  increased  }  What  will  be  the 
saving  in  labor  of  cultivation  and  general  management 
of  the  land  .-*  These  things  and  many  more  enter  into 
the  account  to  be  figured  upon,  all  of  which  will  have 
a  bearing  upon  the  profits,  not  merely  one  year,  but  of 
all  future  years. 

The  non-resident  owner  looks  at  it  from  a  strictly 
investment  standpoint.  The  improvement  will  pay 
him  a  certain  desired  per  cent  on  the  outlay.  If  it  fig- 
ures out  satisfactorily,  the  money  is  placed  i7i  the 
ground  instead  of  upon  it.  Hence  the  necessity  ot 
being  able  to  strike  a  proper  and  correct  balance 
between  estimated  cost  and  estimated  profit. 

It  does  not  come  within  the  province  of  this  chapter 
to  show  what  the  actual  profit  of  such  work  will  be, 


214  ENGINEERING    FOR    LAND    DRAINAGE. 

but  to  outline  the  ground  to  be  gone  over  in  arriving 
at  the  cost  of  drainage  in  any  locality  in  order  that  the 
figures  may  tell  their  own  story  in  a  comprehensive 
way.  It  may  be  remarked  that  some  land  will  pay  a 
large  profit  on  the  cost  of  drainage,  while  other  land 
is  not  worth  it. 

Cost  of  Work  under  Drainage  District  Organization, 

In  case  of  drainage  work  which  must  be  done  under 
the  provisions  of  a  State  drainage  law,  great  care 
should  be  taken  by  the  engineer  and  others  who  have 
direction  of  the  proceedings  to  act  strictly  in  accord- 
ance with  the  directions  of  the  statute  in  every  partic- 
ular. The  plans  and  estimates  form  the  basis  of  all 
subsequent  work  and  should  be  most  carefully  prepared 
and  considered. 

The  cost  of  each  drain,  whether  open  or  of  large  tile, 
which  is  used  for  an  outlet  should  be  estimated  sep- 
arately, and  be  so  scheduled,  for  the  reason  that  in  the 
classification  and  assessment  of  lands  according  to 
benefit  conferred  the  cost  of  separate  drains  should  be 
taken  into  account.  The  cost  of  the  various  items  for 
which  the  law  makes  the  organization  responsible 
should  be  closely  canvassed. 

The  cost  of  engineering,  and  of  administration,  which 
includes  legal  expenses,  fees  of  commissioners,  and 
superintendence,  should  be  added  to  the  cost  of  the 
execution  of  the  work.  This,  of  course,  will  vary  with 
the  size  of  the  district  and  the  legal  difficulties  that 
may  arise,  but  is  usually  not  less  than  1 5  per  cent  of 
the  cost  of  construction. 

Offsetting  the  estimated  expense  of  the  work  should 


ESTIMATES   OF  COST.  21$ 

be  placed  the  estimated  benefits  which  will  result  and 
which  the  engineer  should  be  prepared  to  make.  It  is 
needless  to  say  that  in  order  to  do  this  he  should  be 
conversant  with  the  value  and  management  of  land's. 
A  clear  and  logical  statement  of  cost  and  benefits  in- 
volved in  a  proposed  improvement,  based  upon  facts 
which  will  commend  themselves  in  a  forceful  way  to 
the  court,  and  to  landowners,  will  be  most  valuable, 
and  if  properly  presented  will  do  much  toward  avoid- 
ing legal  controversies  which  arise  by  reason  of  a  mis- 
understanding of  the  facts  that  should  be  considered  in 
the  case. 


CHAPTER   XVI. 
BENEFITS  AND  PROFITS  OF  DRAINAGE. 

The  benefits  and  profits  accruing  from  the  drainage 
of  land  should  be  set  forth  comprehensively  when  the 
Court  or  Board  of  Commissioners  inquires  for  them 
during  investigation  of  any  drainage  project  brought 
before  them  for  consideration,  '*  The  cost  of  the  im- 
provement must  not  be  greater  than  the  benefit,"  is 
the  brief  rule  set  forth  in  the  drainage  laws,  and  is  a 
commercial  maxim  which  is  recognized  in  general 
business.  "  Will  it  pay  ?"  is  imprinted  upon  the  initial 
page  of  every  business  undertaking,  not  in  pleasure  and 
satisfaction,  but  in  dollars  and  cents. 

Some  of  the  benefits  and  resulting  profits  of  the  work 
under  consideration  may  here  be  enumerated  as  sug- 
gestive rather  than  carried  out  in  detail. 

Firmness  and  Fineness  of  Soil. — One  of  the  changes 
produced  by  relieving  the  ground  of  surplus  water  at 
once  noticeable  is  its  increased  firmness.  The  excess 
of  water  recedes  from  the  surface  and  takes  its  place 
lower  in  the  soil,  soon  leaving  a  firm  surface  which  can 
be  passed  over  by  teams  or  live  stock  without  injuring 
the  texture  or  destroying  the  smoothness  of  the  sur- 
face. Not  only  does  this  facilitate  the  culture  and 
management  of  land,  but  the  travelling  public  get  ben- 
efit and  profit  by  reason  of  better  roads  which  result 

216 


BENEFITS   AND   PROFITS   OF   DRAINAGE.        21/ 

from  the  improvement.  The  fineness  of  the  soil  is  in- 
creased by  the  percolation  of  water  from  the  surface 
downward  through  the  soil,  which  permits  air  and  frost 
to  do  their  work  more  effectually  in  disintegrating  the 
particles  of  soil,  reducing  their  size  and  increasing  the 
capacity  of  the  soil  for  moisture.  It  has  been  shown 
in  a  previous  chapter  that  the  per  cent  of  moisture  held 
in  the  soil  after  the  surplus  has  been  drained  off  in- 
creases in  proportion  to  the  fineness  of  the  particles 
composing  it. 

Permits  Earlier  and  More  Timely  Cultivation 

One  and  sometimes  two  weeks'  time  in  the  spring  are 
gained  to  land  and  roads  by  good  underdrainage.  The 
water  from  rains  and  thawing  ice  passes  down  through 
the  soil,  admitting  warm  air  and  fertilizing  rains  to  such 
an  extent  that  the  surface  is  well  prepared  for  the  crops 
requiring  early  planting  much  sooner  than  wet  soils. 
This  is  of  great  advantage  not  only  to  the  cultivation 
on  the  season's  work,  but  often  makes  the  difference 
between  an  excellent  and  profitable  crop  and  an  indif- 
ferent one. 

Produces  Aeration  of  Soil. — A  certain  degree  of  soil 
ventilation  has  been  found  necessary  to  bring  heavy 
lands  to  their  highest  state  of  productiveness.  When 
the  level  of  the  ground  water  is  lowered,  the  roots  of 
plants  penetrate  more  deeply  into  the  soil,  and  as  they 
die  and  decay  leave  a  network  of  channels  extending 
to  the  surface,  through  which  air  circulates,  forming  ven- 
tilating shafts,  as  it  were.  The  interspaces  of  soil  be- 
coming relieved  of  water  are  also  filled  with  air,  which 
carries  with  it  any  fertilizing  gases  it  contains  and  fur- 
nishes oxygen  to  the  roots  of  plants  and  for  the  sup- 


2lS  ENGINEERING   FOR   LAND   DRAINAGE. 

port  of  soil  bacteria,  which  are  now  recognized  as 
playing  such  an  important  part  in  converting  soil 
humus  into  nitrates.  These  elements  of  fertility  are 
absorbed  by  the  soil  and  held  in  readiness  for  the  use 
of  plant-roots.  The  changes  wrought  by  the  passage 
of  water  through  the  soil  and  consequent  circulation  of 
air  are  continuous  processes  and  play  no  unimportant 
part  in  keeping  up  the  productiveness  of  soils.  In 
other  words,  well-drained  soils  do  not  become  ex- 
hausted as  soon  as  undrained  ones,  even  under  the 
most  ordinary  treatment. 

Drainage  Increases  the  Temperature  of  the  Soil. — 
A  soil  cannot  become  warm  until  the  water  upon  its 
surface  is  evaporated  or  thoroughly  warmed  by  the  sun. 
The  cause  is  easily  explained.  A  large  amount  of 
heat  is  used  up  in  evaporating  the  excess  of  water. 
Prof.  F.  H.  King  in  his  work,  ''The  Soil,"  gives  de- 
ductions from  personal  experiments  which  are  valuable 
in  showing  the  effect  of  drainage  upon  soil  tempera- 
ture. He  says:  ''While  lOO  heat  units  will  raise  the 
temperature  of  one  pounds  of  water  through  ioo°  F.,  it 
is  necessary  to  use  966.6  heat  units  to  evaporate  one 
pound  of  water  from  the  soil;  but  this  if  withdrawn 
directly  from  the  cubic  foot  of  saturated  clay  would 
lower  its  temperature  about  10.3°  F.  It  must  be  evi- 
dent, therefore,  that  to  allow  the  surplus  water  to  drain 
away  from  a  field  rapidly,  rather  than  to  hold  it  there 
until  it  has  time  to  evaporate,  must  greatly  favor  the 
warming  of  the  soil." 

He  cites  the  following  observations  showing  the  dif- 
ferences of  temperature  in   the  surface  inch  of  well- 


BENEFITS   AND  PROFITS   OF  DRAINAGE.        219 

drained    sandy  loam  and  an   undrained  black  marsh 
soil,  both  of  them  bare  and  level. 


Date. 

Temp,  of 

Air 

Temp,  of 

Drained 

Soil. 

Temp,  of 

Undrained 

Soil. 

Differences. 

April  24    

60.5°  F. 
64.0° F. 

45-°! F- 
53.0° F. 

66.50°  F. 
70.00° F. 
50.00°  F. 
55.00° F. 

54.00°  F. 
58.00° F. 
44.00° F. 
5o.75°F. 

12.50°  F. 

12.00°  F. 

6 . 00°  F 

"     25 

"     26 

"      27 

4.25*'F. 

The  above  observations  are  upon  unlike  soils,  but  the 
range  of  differences  in  temperature  between  a  drained 
and  undrained  soil  from  which  the  surface-water  has 
been  removed  may  be  taken  at  from  5  to  10  degrees. 

Drainage  Prevents  a  Large  Waste  of  Fertility 
by  Surface  Washing. — The  object  of  all  drainage 
should  be  to  remove  all  surplus  water  through  the  soil, 
not  over  it,  thereby  preventing  loss  by  washing  away 
the  fine  soil  particles  which  constitute  its  richest  part. 
The  drained  soil  acts  as  a  filter  to  arrest  all  the  fertility 
which  may  be  held  in  suspension  by  the  water  to  be 
removed. 

Increases  the  Depth  of  Soil. — A  drained  soil  be- 
comes renovated — opened  up,  so  to  speak,  to  the  full 
depth  to  which  it  is  drained.  An  additional  field  is 
opened  up  for  the  use  of  plant-roots,  giving  them  a 
larger  range  from  which  to  obtain  both  food  and 
moisture. 

A  Drained  Soil  Resists  Drought.— With  reference 
to  the  value  of  drainage  for  enabling  soils  to  resist  the 
inroads  of  drought,  experience  confirms  what  we  might 
expect  would  be  true  from  the  general  effects  which 
drainage  has  upon  the  soil.     The  additional  fineness  of 


220  ENGINEERING   FOR   LAND   DRAINAGE. 

soil  produced  which  makes  it  capable  of  retaining  a 
greater  amount  of  capillary  water,  the  greater  depth  of 
soil  from  which  plants  may  draw  nutriment,  the  circu- 
lation through  the  soil  of  air  from  which  the  moisture 
is  condensed  in  its  cooler  recesses,  all  contribute  to 
the  power  of  a  drained  soil  to  resist  the  effects  of  a 
protracted  dry  spell  during  the  growing  season. 

The  experience  of  farmers  who  have  drained  clay  or 
alluvial  soils  sustains  these  conclusions  as  to  value  of 
underdrainage  in  time  of  drought. 

Benefits  from  Open  Channels. — Their  value  consists 
in  making  more  complete  drainage  possible.  When- 
ever the  value  of  complete  underdrainage  is  estab- 
lished, the  value  of  open  ditches  is  established  if  they 
become  a  necessity  for  properly  carrying  out  the  work. 
In  the  absence  of  natural  receiving  channels,  artificial 
ones  must  be  constructed,  or  old  natural  channels  im- 
proved so  that  drainage  may  be  completed  by  the  own- 
ers of  individual  tracts  of  land.  Open  ditches  often 
serve  as  the  outlet  of  the  soil  drainage  of  towns  and  vil- 
lages, or  for  the  effluent  of  sewage  after  it  has  been 
treated  or  filtered  in  such  a  manner  and  so  effectively 
that  it  will  be  harmless.  In  such  cases  assessment 
should  be  made  on  the  corporation  for  its  share  of  the 
cost  of  the  ditch.  Such  an  assessment  cannot  be  made 
upon  the  same  basis  as  upon  agricultural  lands,  but 
upon  the  valuation  of  the  property  of  the  corporation 
compared  with  the  value  of  a  similar  area  of  farm 
property. 

These  ditches  are  of  marked  benefit  to  the  highways 
of  the  tract  which  they  drain  in  giving  outlets  for  road 
drains  and  in  the  work  incidentally  effected  by  the  gen- 


BENEFITS   AND   PROFITS   OF   DRAINAGE.         221 

eral  system.  The  highway  as  such  should  be  assessed 
for  these  benefits,  which  sum  should  be  paid  out  of  the 
general  road  fund. 

Profits  of  Drainage.  What  are  They?— On  the 
farm  they  are : 

1.  Proceeds  from  waste  land  which  before  drainage 
produced  nothing — a  clear  gain  of  land  which  is  worth 
as  much  for  productive  purposes  as  the  balance  of  the 
farm. 

2.  Doubling  the  annual  production  of  many  other 
acres  without  increasing  the  cost  of  cultivation. 

3.  Diminishing  the  expense  of  management  by 
reason  of  doing  away  with  broken -up  fields  and  unnec- 
essary open  ditches. 

All  of  these  represent  a  money  value  to  the  farm 
which  can  be  readily  estimated  if  analyzed  and  placed 
in  order  with  a  value  attached  to  each  item. 

Regarding  the  improvement  of  larger  tracts  which 
have  no  productive  value  until  drained  the  expense 
account  may  be  outlined  as  follows : 

1 .  First  cost  of  land. 

2.  Cost  of  draining  to  fit  it  for  production. 

3.  Interest  on  purchase  price  until  it  is  prepared 
to  produce. 

4.  Taxes  until  it  can  produce. 

5.  Clearing,  if  timbered. 

6.  Houses,  barns,  fences,  etc. ,  necessary  to  fit  it  up 
into  productive  farms. 

The  sum  of  these  expenses  will  represent  the  cost 
of  the  land  ready  for  producing  a  crop.  If  the  land  is 
fertile  there  can  be  no  question  regarding  the  value  of 
the  investment  unless   the   ultimate   cost  runs  higher 


222  ENGINEERING   FOR   LAND   DRAINAGE. 

than  other  land  which  is  improved  in  a  similar  manner, 
which  is  rarely  the  case.  The  improvement  of  land  of 
this  character  is  susceptible  of  being  figured  out  with 
reasonable  accuracy  beforehand.  Two  items  in  the 
above  schedule  should  receive  particular  attention, 
namely,  the  cost  and  efficiency  of  the  proposed  drainage, 
and  the  value  of  the  soil  for  productive  purposes  when 
drained. 

What  will  it  cost  to  reclaim  it  and  what  will  it  pro- 
duce after  it  is  reclaimed  and  improved  ?  are  the  points 
to  be  investigated  by  the  engineer  and  purchaser. 

Conclusion, 

It  has  been  the  aim  of  the  writer  of  this  book  to 
place  within  the  reach  of  the  engineer,  the  thorough 
agriculturist,  and  careful  buyer  of  unimproved  land 
such  information  and  practical  details  of  work  as  will 
enable  them  to  engage  in  the  work  of  land  drainage 
intelligently  and  successfully.  All  has  not  been  said 
which  might  be  said  upon  this  important  subject. 
Doubtless  many  details  have  been  omitted  which  it 
would  have  been  well  to  insert.  Be  that  as  it  may,  the 
book  is  not  loaded  up  with  useless  matter  nor  with  un- 
tried theories,  but  is  practical  and  easily  understood. 


INDEX. 


PAGB 

Acre,  number  of  feet  of  drains  required  on 94 

Agriculturist,  the 5 

Area  drained  by  a  main 140 

Assessment  roll,  classification  for 204 

,  example  of 207 

,  how  made 205 

Barnyards,  drainage  of 179 

Bench-marks,  definition  of 53 

,  location  of 167 

Beardmore 129 

Bearing  of  a  line 80 

Berm,  definition  of 165 

width  of , 166 

Blue-prints,  how  to  make 102 

Bottom  of  ditch,  grading  and  shaping 122 

Brick,  use  of,  on  roads 197 

Brown,  J.  B 195 

Catch-basins,  use  of 180 

Cellars,  drainage  of 182 

,  plan  for  draining 183 

Chain,  band , 55 

,  link 55 

Chamberlain,  W.  1 186 

Checks  on  work 77 

Classification  of  lands,  map  showing 206 

,  method  of 204 

,  principles  of 203 

f  theory  of 202 

•  223 


224  INDEX. 

PAGE 

Commissioners,  work  of 206 

Compass,  description  of 79 

,  how  used 80 

notes,  how  kept ' 83,  84 

Computing  excavations,  method  of 169 

Construction  of  drains,  difficulties  of 109,  1 10 

Contour  lines,  description  of 65 

map 69 

survey , 66 

Contracts  for  construction  work 120 

Contract,  form  of 125 

Copies  of  maps,  how  made loi,  102 

Cost,  estimates  of 209 

of  digging  ditch  and  laying  tile 212 

of  hauling  and  distributing  tile 211 

of  superintending  work 212 

Crops,  increase  of. 9 

Cross-drains  for  roads. 193 

Cross-sectioning,  form  of  book  for 168 

,  method  of 168 

Culverts,  sewer-pipe  for 193 

Curve,  degree  of 154 

,  how  run 156 

,  proper,  for  6pen  ditches 155 

Curves  in  tile-drain  lines 72 

Cut  for  ditches,  how  found 86 

Datum,  common 77 

plane 50 

Declination  of  magnetic  needle,  how  corrected 83 

Depth  of  drains,  discussion  of 89 

Ditch  for  tile,  how  to  dig 106 

Ditches,  bottom  width  of 158 

,  curvature  of 154 

,  filling 114 

,  special  forms  of 177,  178 

Divide,  how  to  find  natural 200 

Drafting  instruments 96 

Drainage  basin,  how  designated 64 

Drainage  district,  boundary  of 199 

,  large  tile  for. ... 201 


INDEX.  225 

PACK 

Drainage  district,  mutual 208 

,  provision  of  outlets  for 201 

Drainage  engineer,  the i 

Drainage,  civilizing  effects  of 2 

,  growth  of 2 — 6 

,  profits  of 216 

Drains,  avoid  short  crooks  in. ...  ^ ,  4g 

,  how  designated 73 

,  names,  for  in  systems 42 

,  open... 150 

Drop,  how  proportioned 87 

Drought  and  drainage ; 219 

Estimates  for  drainage  districts 214 

of  number  of  feet  of  drains  per  acre 94 

of  total  cost 214 

preliminary 94 

Excavation,  computing. 169 

Experimental  investigations 24 

Experiments  at  Maryland  Station 25 

at  Germantown,  Ohio 30 

at  Newbern,  N.  C 28 

at  Litiz,  Pa 30 

at  Lexington,  Ky 30 

at  Washington,  D.  C 29 

at  Windsor,  Conn 30 

at  Madison,  Wis 38,  39,  40 

Fall,  available 85 

definition  of 85 

Fertilizers,  effect  upon  soil  moisture 30 

Field-notes,  form  for 56,  76 

how  kept 74 

Flag-poles 55 

Flow  of  water  through  pipes 126 

tile  drains 130 

Formula,  application  of. 162 

,  examples  of  use  of,  for  open  drains 164 

for  quantity  of  discharge 130 

for  velocity  of  flow  in  open  drains 161 

Formulas  for  velocity  of  flow 128,  129,  132 


226  INDEX. 

PAGE 

Frequency  of  drains,  discussion  of 92 

Frozen  ground,  percolation  of  water  through 31 

Grade,  how  computed 36 

locating,  for  open  ditches 166 

uniform 86 

Grade  of  drain,  change  of. 87 

how  expressed ^ 85 

Grading  ditches,  line  method 103 

target  method 105 

Guide-stakes,  lining  and  setting. 72 

material  for 71 

numbering 73 

Gumbo 17 

Hand-axe 55 

Hard-pan 18 

Health,  effect  of  drainage  on 9 

Indiana  Bureaa  of  Statistics,  report  of 9 

Inspection  of  ditches 176 

Investment,  profit  on 213 

Junction  of  a  shallow  ditch  with  a  deep  one 177 

Junctions  with  drains,  how  made 108,  148 

King,  F.  H 40,  218 

Land  drainage,  kinds  of 35 

questions  concerning 36 

Landowners  should  know  drainage  principles 10 

Laterals,  avoid  short 49 

location  of 48 

size  of 144 

velocity  of  flow  in 145 

Lettering,  for  maps loi 

fi-ee-hand , lOi 

Level  line 52 

Levelling,  definition 52 

Level  notes,  form  of. 58 

how  to  prove 59 


INDEX. 


227 


PAGE 

Limitations  of  size  of  tile 141 

grade 141,  142 

length  of  drain 141^  142 

Line  of  saturation,  variation  of 40 

Lining  grade-stakes. y2 

Locating  drains,  principles  of 47 

lateral  drains 48 

main  drains 47 

open  drains 150,  i66 

Macadam 188 

Machines  for  digging  tile  ditches 1 19 

Mapping  drainage 95 

Map,  a  sketch 95 

how  to  make 98 

scale  of 68 

the  finished. 95 

Meridian  determined  by  equal  shadows  of  the  sun 82 

old  lines 81 

Movement  of  groimd-water 27,  40,  41 

Muck 18 

Notes,  form  for 76,  168 

how  kept 74,  76 

on  curves • 154,  155 

Open  channels,  benefit  of 220 

Open  ditches,  capacity  of 159 

depth  of. 158 

form  of 157 

grade  for 150 

quantity  of  water  to  be  removed  by 160 

velocity  of  flow  in 152 

Orchards,  drainage  of 184 

plan  of  drains  for 185 

Outlet,  box  protection  for "6 

stone  abutment  for "7 

Outlets,  submerged i" 

Overflow,  provision  for. 145 

Paved  roads • ^95 


228  INDEX. 

PAGB 

Peat i8 

Plat  of  a  survey 63 

Platting  a  survey  from  field-notes 96 

compass  bearings 97 

Plow,  use  of,  in  draining 113,  212 

Prices  of  drain-tile 210 

Profile,  how  made * 78 

locating  grades  on 78 

use  of 7^ 

Profits,  estimated 213 

of  drainage 22x 

Quantity  of  water,  formula  for 130 

,  to  be  removed  by  drains 133 

Rainfall,  provision  for  unusual 145 

Record  of  work 64 

Residence  groimds,  drainage  of 184 

Road  drainage,  essential  elements  of 188 

importance  of •. 187 

Road  inquiry,  office  of » 187 

Roads,  brick-paved 197 

gravel  and  earth 199 

surface,  ditches  for 188 

form  of 191 

Rod,  speaking,  description  of. 54 

target 53 

use  of. 53 

Roof-water , , , I79 

Roots  in  drains. 185 

Saturation,  line  of,  between  drains 39 

plane  of 38 

Seepage,  drain  for 192 

Sewer-pipe  for  culverts 193 

how  laid.. 194 

Side  ditch,  discharge  of 176 

Sights,  length  of.  .^ . .  . . ,  ^ , 74 

Silt-basin,  effect  upon  flow .,...,,..,.,.....?..  •  * « .  ^^^ 

use  of. I  r8 

Sketch-plat 75 


INDEX.  229 

PAGB 

Slope-stakes,  notes  for 168 

setting i68 

Soil,  aeration  of 217 

alluvial le 

carbonic  acid  in Iq 

conservation  of  moisture  of  the 33 

definition  of 19 

empty  space  in 26 

firmness  of 217 

heaving  of 32 

Soils,  kinds  of 17 

organic  matter  in 16 

origin  of 12 

sedentary 14 

structure  of 25 

temperature  of 218 

transported 15 

Specifications  for  construction  of  drains 121-123 

Spirit-level 53 

Staking  out  drains 71 

Steam-dredges,  kinds  of. 173,  174 

operation  of 173,  174 

Subsoil 19,  20 

Survey,  compass 79,  80 

Surveys,  for  open  ditches , 166 

tile  drains Ti,  73 

topography 59>  64 

practical  hints  on 67,  68 

System,  double-main 45 

gridiron 43 

grouping 43 

natural 42 

single-line .^  •     4^ 

Systems  of  tile  drains  discussed 42 

Teams,  ditching  with, I7S 

Telford 188 

Tile  drains,  cleaning no 

how  water  enters 37 

inspecting 1 12 

Tile-hook 108 


230  INDEX. 

PACK 

Tile,  how  to  lay 108 

junction 148 

secured  in  place 109 

selection  of. 147 

tabulating  sizes 149 

thickness  of  walls  for 148 

Tools  for  making  drains 109 

Topographical  survey  for  contour  lines 65 

with  boundary  line  as  base 62 

central  line  as  base.. 61 

watercourse  as  base 62 

Topography,  survey  for , 60 

Tracings,  how  made loi 

Turning-points 58 

Underdrainage,  effect  on  health 9 

necessity  for 36 

Unfinished  drains,  heavy  rains  on 113 

Velocity,  flow  in  open  channels 152 

maximum 152 

mean 153 

of  falling  bodies 127 

relation  of  breadth  and  depth  of  channel  to 153 

Waste  banks,  breaks  in 165 

treatment  of 165 

Water,  action  of,  at  ditch  curves 156 

capillary 21 

drainage 21 

hydrostatic 21 

movement  of 22,  23,  27 

soil-space  occupied  by 22 

sources  of 41 

Weight  of  drain-tile 210 

Weight  of  water 139 

Weisbach 128 

Yards,  cubic,  in  one  rod  of  tile  ditch 2X2 


INDEX.  231 

TABLES. 


PAGE 


1.  Decimals  of  a  foot  reduced  to  inches 89 

2.  Areas  of  tile  in  square  feet 137 

3.  Head  in  inches  per  100  feet  reduced  to  feet  per  100  feet  and  feet 

per  mile 137 

4.  Contents  of  tile  in  one  foot  of  length 137 

5.  Cubic  feet  per  second  which  must  be  discharged  from  a  drain  to 

relieve  one  acre  of  land  of  various  depths  of  water  in  24  hours.    138 

6.  Limit  of  size  of  tile  to  grade  and  length 142 

7.  Excavation  tables 170 


ILLUSTRATIONS. 

Figure  i.   Section  showing  effect  of  clay  subsoil  upon  natural  drain- 
age   21 

2 .  Heaving  of  wet  soils 33 

3.  Line  of  saturation  between  tile  drains 39 

4 .  Natural  system 43 

5 .  Grouping  system 44 

6.  Gridiron  system 45 

7 .  Double-main  system ^  45 

8 .  Single-line  system 46 

9.  Water-line  in  retentive  clay  soils 48 

10.  Self-reading  rod 54 

11 .  Levelling 56 

12.  Topography  from  central  base  line 63 

13 .  Topography  by  contours 69 

14.  Guide-stakes  and  hubs 72 

15 .  Profile  of  Main  A 7^ 

16.  Taking  compass  bearings 80 

17.  Obtaining  meridian  by  equal  shadows  of  the  sun 82 

18 .  Angle  and  drop  for  tile  drain 88 

19 .  Effect  of  drains  on  open  soils 90 

20.  Drainage  of  a  40-acre  field 92 

21 .  Platting  compass  bearings .' 97 

22.  Drainage  plan  for  a  farm  of  160  acres  of  level  land 99 

23..   Conventional  signs  used  to  represent  topography lOO 

24.  Grading  by  gauge  and  line    104 

Four-inch  lateral  drain fficing  104 

25 .  Grading  by  sight-line  and  target 105 


2  32-  INDEX. 

PAGE 

Figure  26.   Method  of  using  tile-hook 108 

27.  Section  of  stone  abutment  for  drain  outlet 117 

28.  Box  outlet  for  tile  drain 117 

Digging  a  ditch  for  twelve-inch  tile facing  144 

Laying  twelve-inch  drain-tile ''  146 

A  dredged  drainage-ditch  ten  years  after  excavation   <'  152 

29 .  Proper  curve  for  open  ditches 155 

30.  Action  of  current  on  ditch-banks  at  curves 156 

31 .  Section  of  ditches  with  computations 163 

32.  Junction  of  shallow  ditch  with  deep  main 177 

33 .  Sections  of  open  ditches 178 

34.  Catch-basin  for  stirface  drainage 181 

35 .  Catch-basin  constructed  of  sewer-pipe 182 

36.  Orchard  drainage 185 

37.  Location  for  surface  ditches  and  tile  drains  in  road  con- 

struction      191 

38.  Tile  drain  to  intercept  seepage  water 192 

39.  Combined  brick  and  clay  road 197 

Twenty-inch  drain-tile  distributed  for  laying  through  a 

swamp facing  200 

Thirty-inch  drain-tile  distributed  along  the  line  of  a  sur- 
veyed drain facing  202 

40.  Tile  drain  with  a  relief  surface  ditch 202 

41 .  Classification  map  of  a  drainage  district 206 


\ 


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Jlliott, 

C.G. 

JSOX 

Enginee 

ring 

for 

land 

drainage. 

'>r     • 

m^ 

* 

i 

/ 

Arcs  or 

'S5859      . 

^ 

/ 

/ 

1 

/ 

,15 

4.' 

/ 

/ 

^^H 

